Hallo Stefan77x,
verwendest Du Linux? Dann müßte das das bekannte Browser-Problem sein. Ansonsten müßtest Du mal im Error-Log nachsehen (steht im Arbeitsverzeichnis unter Log bzw. im User-Verzeichnis unter .fakturama/.metadata).

Hallo, ist Windows. Habe auch schon eine Neuinstallation versucht.

und was steht im Log?

Kannst damit was anfangen?

!ENTRY org.eclipse.ui 4 4 2016-01-17 14:17:13.928
!MESSAGE Invalid preference page path: Security

!ENTRY org.eclipse.ui.workbench 4 2 2016-01-17 14:17:48.165
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.ui.workbench".
!STACK 0
java.lang.NoClassDefFoundError: Could not initialize class com.sebulli.fakturama.data.Data
at com.sebulli.fakturama.ApplicationWorkbenchWindowAdvisor.postWindowClose(ApplicationWorkbenchWindowAdvisor.java:181)
at org.eclipse.ui.internal.WorkbenchWindow.fireWindowClosed(WorkbenchWindow.java:1388)
at org.eclipse.ui.internal.WorkbenchWindow.hardClose(WorkbenchWindow.java:1731)
at org.eclipse.ui.internal.WorkbenchWindow.busyClose(WorkbenchWindow.java:730)
at org.eclipse.ui.internal.WorkbenchWindow.access$0(WorkbenchWindow.java:715)
at org.eclipse.ui.internal.WorkbenchWindow$6.run(WorkbenchWindow.java:867)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.ui.internal.WorkbenchWindow.close(WorkbenchWindow.java:865)
at org.eclipse.jface.window.WindowManager.close(WindowManager.java:109)
at org.eclipse.ui.internal.Workbench$18.run(Workbench.java:1114)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.ui.internal.Workbench.busyClose(Workbench.java:1111)
at org.eclipse.ui.internal.Workbench.access$15(Workbench.java:1040)
at org.eclipse.ui.internal.Workbench$25.run(Workbench.java:1284)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.ui.internal.Workbench.close(Workbench.java:1282)
at org.eclipse.ui.internal.Workbench.close(Workbench.java:1254)
at org.eclipse.ui.internal.WorkbenchWindow.busyClose(WorkbenchWindow.java:727)
at org.eclipse.ui.internal.WorkbenchWindow.access$0(WorkbenchWindow.java:715)
at org.eclipse.ui.internal.WorkbenchWindow$6.run(WorkbenchWindow.java:867)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.ui.internal.WorkbenchWindow.close(WorkbenchWindow.java:865)
at org.eclipse.jface.window.Window.handleShellCloseEvent(Window.java:741)
at org.eclipse.jface.window.Window$3.shellClosed(Window.java:687)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:98)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1077)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1062)
at org.eclipse.swt.widgets.Decorations.closeWidget(Decorations.java:308)
at org.eclipse.swt.widgets.Decorations.WM_CLOSE(Decorations.java:1677)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4530)
at org.eclipse.swt.widgets.Canvas.windowProc(Canvas.java:341)
at org.eclipse.swt.widgets.Decorations.windowProc(Decorations.java:1610)
at org.eclipse.swt.widgets.Shell.windowProc(Shell.java:2061)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4972)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2526)
at org.eclipse.swt.widgets.Shell.callWindowProc(Shell.java:498)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Canvas.windowProc(Canvas.java:341)
at org.eclipse.swt.widgets.Decorations.windowProc(Decorations.java:1610)
at org.eclipse.swt.widgets.Shell.windowProc(Shell.java:2061)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4972)
at org.eclipse.swt.internal.win32.OS.DefWindowProcW(Native Method)
at org.eclipse.swt.internal.win32.OS.DefWindowProc(OS.java:2526)
at org.eclipse.swt.widgets.Shell.callWindowProc(Shell.java:498)
at org.eclipse.swt.widgets.Control.windowProc(Control.java:4623)
at org.eclipse.swt.widgets.Canvas.windowProc(Canvas.java:341)
at org.eclipse.swt.widgets.Decorations.windowProc(Decorations.java:1610)
at org.eclipse.swt.widgets.Shell.windowProc(Shell.java:2061)
at org.eclipse.swt.widgets.Display.windowProc(Display.java:4972)
at org.eclipse.swt.internal.win32.OS.DispatchMessageW(Native Method)
at org.eclipse.swt.internal.win32.OS.DispatchMessage(OS.java:2531)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3752)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2701)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2665)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2499)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:679)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:668)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at com.sebulli.fakturama.Application.start(Application.java:39)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:344)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
at org.eclipse.equinox.launcher.Main.run(Main.java:1410)
!SESSION 2016-01-17 14:23:23.358 -----------------------------------------------
eclipse.buildId=unknown
java.version=1.7.0_67
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=de_DE
Command-line arguments: -os win32 -ws win32 -arch x86

!ENTRY org.eclipse.ui 4 4 2016-01-17 14:23:33.104
!MESSAGE Invalid preference page path: Security

!ENTRY org.eclipse.osgi 2 1 2016-01-17 14:24:35.719
!MESSAGE NLS unused message: Wollen in: org.eclipse.equinox.internal.p2.ui.messages
!SESSION 2016-01-17 14:54:50.748 -----------------------------------------------
eclipse.buildId=unknown
java.version=1.7.0_67
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=de_DE
Command-line arguments: -os win32 -ws win32 -arch x86

!ENTRY org.eclipse.ui.workbench 4 0 2016-01-17 14:55:16.982
!MESSAGE Unable to create view ID com.sebulli.fakturama.views.datasettable.viewListTable: Es wurde eine unerwartete Ausnahmebedingung ausgelöst.
!STACK 0
java.lang.NullPointerException
at com.sebulli.fakturama.views.datasettable.ViewListTable.createPartControl(ViewListTable.java:77)
at org.eclipse.ui.internal.ViewReference.createPartHelper(ViewReference.java:375)
at org.eclipse.ui.internal.ViewReference.createPart(ViewReference.java:229)
at org.eclipse.ui.internal.WorkbenchPartReference.getPart(WorkbenchPartReference.java:595)
at org.eclipse.ui.internal.ViewReference.getView(ViewReference.java:198)
at org.eclipse.ui.internal.WorkbenchPage.findView(WorkbenchPage.java:1989)
at com.sebulli.fakturama.ApplicationWorkbenchAdvisor.refreshView(ApplicationWorkbenchAdvisor.java:86)
at com.sebulli.fakturama.misc.CountryCodes$1.run(CountryCodes.java:83)
at org.eclipse.swt.widgets.Synchronizer.syncExec(Synchronizer.java:180)
at org.eclipse.ui.internal.UISynchronizer.syncExec(UISynchronizer.java:150)
at org.eclipse.swt.widgets.Display.syncExec(Display.java:4683)
at com.sebulli.fakturama.misc.CountryCodes.loadFromRecouces(CountryCodes.java:79)
at com.sebulli.fakturama.data.Data.fillWithInitialData(Data.java:221)
at com.sebulli.fakturama.data.Data.(Data.java:167)
at com.sebulli.fakturama.data.Data.(Data.java:33)
at com.sebulli.fakturama.views.datasettable.ViewContactTable.createPartControl(ViewContactTable.java:96)
at org.eclipse.ui.internal.ViewReference.createPartHelper(ViewReference.java:375)
at org.eclipse.ui.internal.ViewReference.createPart(ViewReference.java:229)
at org.eclipse.ui.internal.WorkbenchPartReference.getPart(WorkbenchPartReference.java:595)
at org.eclipse.ui.internal.PartPane.setVisible(PartPane.java:313)
at org.eclipse.ui.internal.ViewPane.setVisible(ViewPane.java:534)
at org.eclipse.ui.internal.presentations.PresentablePart.setVisible(PresentablePart.java:180)
at org.eclipse.ui.internal.presentations.util.PresentablePartFolder.select(PresentablePartFolder.java:270)
at org.eclipse.ui.internal.presentations.util.LeftToRightTabOrder.select(LeftToRightTabOrder.java:65)
at org.eclipse.ui.internal.presentations.util.TabbedStackPresentation.selectPart(TabbedStackPresentation.java:473)
at org.eclipse.ui.internal.PartStack.refreshPresentationSelection(PartStack.java:1245)
at org.eclipse.ui.internal.PartStack.createControl(PartStack.java:662)
at org.eclipse.ui.internal.PartStack.createControl(PartStack.java:570)
at org.eclipse.ui.internal.PartSashContainer.createControl(PartSashContainer.java:568)
at org.eclipse.ui.internal.PerspectiveHelper.activate(PerspectiveHelper.java:272)
at org.eclipse.ui.internal.Perspective.onActivate(Perspective.java:981)
at org.eclipse.ui.internal.WorkbenchPage.onActivate(WorkbenchPage.java:2714)
at org.eclipse.ui.internal.WorkbenchWindow$28.run(WorkbenchWindow.java:3030)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.ui.internal.WorkbenchWindow.setActivePage(WorkbenchWindow.java:3011)
at org.eclipse.ui.internal.WorkbenchWindow$21.runWithException(WorkbenchWindow.java:2297)
at org.eclipse.ui.internal.StartupThreading$StartupRunnable.run(StartupThreading.java:31)
at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:135)
at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4140)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3757)
at org.eclipse.ui.application.WorkbenchAdvisor.openWindows(WorkbenchAdvisor.java:803)
at org.eclipse.ui.internal.Workbench$33.runWithException(Workbench.java:1600)
at org.eclipse.ui.internal.StartupThreading$StartupRunnable.run(StartupThreading.java:31)
at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:135)
at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4140)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3757)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2609)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2499)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:679)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:668)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at com.sebulli.fakturama.Application.start(Application.java:39)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:344)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
at org.eclipse.equinox.launcher.Main.run(Main.java:1410)

Hm. Irgendwas ist mit den Daten nicht in Ordnung. Probier mal bitte folgendes (auf einer Kommandozeile im Fakturama-Verzeichnis):

Fakturama -clean

Wenn das nicht hilft, mal bitte das Verzeichns ./fakturama im Benutzerverzeichnis umbenennen und Fakturama dann neu starten.
Zusätzlich bitte mal mit dem Datenbank-Checker die DB prüfen.

Der erste Vorschlag brachte nichts.

Der zweite forderte mich auf ein Datenverzeichnis zu wählen. Habe ich ein neues genommen, startete das Programm. Habe ich das bisherige wird eingestellt, war der Fehler wieder da.

Das Ergebnis des Datenchecks ist folgendes. Wenn ich jetzt die Bereinigung laufen lasse, dann sind meine Daten fast alle weg, oder?

10')
ERROR in 322: ID -1 not found in table PAYMENTS, but there is a reference from CONTACTS('Riebel')
[...]
Checking relationship DOCUMENTS(ADDRESSID) -> CONTACTS
Checking relationship DOCUMENTS(PAYMENTID) -> PAYMENTS
Checking relationship DOCUMENTS(SHIPPINGID) -> SHIPPINGS
Checking relationship DOCUMENTS(INVOICEID) -> DOCUMENTS
Checking relationship ITEMS(PRODUCTID) -> PRODUCTS
Checking relationship ITEMS(OWNER) -> DOCUMENTS
Checking relationship ITEMS(VATID) -> VATS
Checking relationship SHIPPINGS(VATID) -> VATS
Checking relationship EXPENDITUREITEMS(VATID) -> VATS
Checking relationship RECEIPTVOUCHERITEMS(VATID) -> VATS
Checking relationship DOCUMENTS(ITEMS) -> ITEMS
67 errors found.

H:DocumentsFKFFakturamaFKFDatabase>

Habe die vorletzte Datensicherung zurückgespielt. Jetzt geht es wieder. Allerdings ist mir aufgefallen, dass die Rechnungsnummern nicht richtig hochgezählt werden.

ich hab mal die Daten etwas gekürzt, bitte vorsichtig sein mit persönlichen Daten.

Die Rechnungsnummern kannst Du über die Einstellungen (Nummernkreise) neu setzen.