PHP-Eclipse: Internen PHP Browser verwenden?

[*Markus]

Hallo,

seit Stunden probiere ich herum, wie ich wohl dem PHP Browser in Eclipse beibringen kann, PHP-Scripts in Eclipse intern darzustellen, anstatt diese mit Firefox anzeigen zu lassen.
Auf meinem Notebook funktioniert das problemlos. Ich weiß aber nicht, was da anders ist. Auf meinem Standpc schaffe ich das nicht. Ich kann maximal mit Rechtsklick->Open PHP browser das Script in Firefox darstellen lassen.
Mit Rechtsklick->Open With other->PHP Web Browser bekomme ich "Could not launch internal Web Browser, Please set an external Browser in the preferences".
Der Stack-Trace ist der Folgende:
java.lang.NullPointerException
 at net.sourceforge.phpeclipse.webbrowser.internal.WebBrowser.getURL(WebBrowser.java:666)
 at net.sourceforge.phpeclipse.webbrowser.internal.WebBrowser.navigate(WebBrowser.java:347)
 at net.sourceforge.phpeclipse.webbrowser.internal.WebBrowser.setURL(WebBrowser.java:385)
 at net.sourceforge.phpeclipse.webbrowser.internal.WebBrowser.setURL(WebBrowser.java:418)
 at net.sourceforge.phpeclipse.webbrowser.internal.WebBrowserEditor.createPartControl(WebBrowserEditor.java:106)
 at org.eclipse.ui.internal.EditorReference.createPartHelper(EditorReference.java:661)
 at org.eclipse.ui.internal.EditorReference.createPart(EditorReference.java:426)
 at org.eclipse.ui.internal.WorkbenchPartReference.getPart(WorkbenchPartReference.java:592)
 at org.eclipse.ui.internal.EditorReference.getEditor(EditorReference.java:263)
 at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditorBatched(WorkbenchPage.java:2739)
 at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditor(WorkbenchPage.java:2651)
 at org.eclipse.ui.internal.WorkbenchPage.access$13(WorkbenchPage.java:2643)
 at org.eclipse.ui.internal.WorkbenchPage$10.run(WorkbenchPage.java:2595)
 at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:67)
 at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2590)
 at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2574)
 at org.eclipse.ui.actions.OpenWithMenu.openEditor(OpenWithMenu.java:340)
 at org.eclipse.ui.actions.OpenWithMenu.access$0(OpenWithMenu.java:328)
 at org.eclipse.ui.actions.OpenWithMenu$3.handleEvent(OpenWithMenu.java:226)
 at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66)
 at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1101)
 at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3319)
 at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:2971)
 at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2389)
 at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2353)
 at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2219)
 at org.eclipse.ui.internal.Workbench$4.run(Workbench.java:466)
 at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:289)
 at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:461)
 at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
 at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:106)
 at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:169)
 at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:106)
 at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:76)
 at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:363)
 at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:176)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:597)
 at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:508)
 at org.eclipse.equinox.launcher.Main.basicRun(Main.java:447)
 at org.eclipse.equinox.launcher.Main.run(Main.java:1173)

Was kann ich tun?

Markus