I created a new Flex project, added some SWC libraries and some source paths,
and when I pressed FInished I got a fatal error: open editor: Assertion failed
opening mxml file. Even if I close Eclipse and try to re-open it I get the same
error. I am using the Flex plug-in to Eclipse. I've been using this environment
for weeks with Actionscript projects. The thing that is different here is this
is an MXML Flex project. Desperately need help as I am blocked.

org.eclipse.jface.util.Assert$AssertionFailedExcep tion: Assertion failed:
at org.eclipse.jface.util.Assert.isTrue(Assert.java:1 85)
at org.eclipse.jface.util.Assert.isTrue(Assert.java:1 70)
at
com.adobe.flexbuilder.editors.derived.editor.FlexM ultiPageEditorPart.setActivePa
ge(FlexMultiPageEditorPart.java:569)
at
com.adobe.flexbuilder.editors.common.editor.CodeAn dDesignEditor.setActivePage(Co
deAndDesignEditor.java:643)
at
com.adobe.flexbuilder.editors.mxml.MXMLEditor.setA ctivePage(MXMLEditor.java:483)
at
com.adobe.flexbuilder.editors.derived.editor.FlexM ultiPageEditorPart.createPartC
ontrol(FlexMultiPageEditorPart.java:235)
at
com.adobe.flexbuilder.editors.common.editor.CodeAn dDesignEditor.createPartContro
l(CodeAndDesignEditor.java:162)
at
org.eclipse.ui.internal.EditorReference.createPart Helper(EditorReference.java:66
1)
at
org.eclipse.ui.internal.EditorReference.createPart (EditorReference.java:428)
at
org.eclipse.ui.internal.WorkbenchPartReference.get Part(WorkbenchPartReference.ja
va:594)
at
org.eclipse.ui.internal.EditorAreaHelper.setVisibl eEditor(EditorAreaHelper.java:
263)
at
org.eclipse.ui.internal.EditorManager.setVisibleEd itor(EditorManager.java:1410)
at
org.eclipse.ui.internal.EditorManager$5.runWithExc eption(EditorManager.java:944)
at
org.eclipse.ui.internal.StartupThreading$StartupRu nnable.run(StartupThreading.ja
va:31)
at org.eclipse.swt.widgets.RunnableLock.run(RunnableL ock.java:35)
at
org.eclipse.swt.widgets.Synchronizer.runAsyncMessa ges(Synchronizer.java:133)
at org.eclipse.swt.widgets.Display.runAsyncMessages(D isplay.java:3342)
at org.eclipse.swt.widgets.Display.readAndDispatch(Di splay.java:3071)
at
org.eclipse.ui.application.WorkbenchAdvisor.openWi ndows(WorkbenchAdvisor.java:80
3)
at org.eclipse.ui.internal.Workbench$27.runWithExcept ion(Workbench.java:1361)
at
org.eclipse.ui.internal.StartupThreading$StartupRu nnable.run(StartupThreading.ja
va:31)
at org.eclipse.swt.widgets.RunnableLock.run(RunnableL ock.java:35)
at
org.eclipse.swt.widgets.Synchronizer.runAsyncMessa ges(Synchronizer.java:133)
at org.eclipse.swt.widgets.Display.runAsyncMessages(D isplay.java:3342)
at org.eclipse.swt.widgets.Display.readAndDispatch(Di splay.java:3071)
at org.eclipse.ui.internal.Workbench.runUI(Workbench. java:2293)
at org.eclipse.ui.internal.Workbench.access$4(Workben ch.java:2198)
at org.eclipse.ui.internal.Workbench$5.run(Workbench. java:493)
at
org.eclipse.core.databinding.observable.Realm.runW ithDefault(Realm.java:288)
at org.eclipse.ui.internal.Workbench.createAndRunWork bench(Workbench.java:488)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(Pl atformUI.java:149)
at
org.eclipse.ui.internal.ide.application.IDEApplica tion.start(IDEApplication.java
:113)
at
org.eclipse.equinox.internal.app.EclipseAppHandle. run(EclipseAppHandle.java:193)
at
org.eclipse.core.runtime.internal.adaptor.EclipseA ppLauncher.runApplication(Ecli
pseAppLauncher.java:110)
at
org.eclipse.core.runtime.internal.adaptor.EclipseA ppLauncher.start(EclipseAppLau
ncher.java:79)
at
org.eclipse.core.runtime.adaptor.EclipseStarter.ru n(EclipseStarter.java:386)
at
org.eclipse.core.runtime.adaptor.EclipseStarter.ru n(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method)
at
sun.reflect.NativeMethodAccessorImpl.invoke(Native MethodAccessorImpl.java:39)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(De legatingMethodAccessorImpl.jav
a:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.eclipse.equinox.launcher.Main.invokeFramework( Main.java:549)
at org.eclipse.equinox.launcher.Main.basicRun(Main.ja va:504)
at org.eclipse.equinox.launcher.Main.run(Main.java:12 36)