Help Desk Ticket Reference: https://c.na7.visual.force.com/apex/Case_View?id=500A0000008SP5t
Steps to Reproduce: In workspace stored on network filesystem, perform below steps with any existing VDB.
1) Remove model from VDB
2) Immediately add same model back into VDB
Workaround Description: The network filesystem is mapped to a drive letter in a Windows environment.  Instead of using the UNC Path for the model, use the mapped drive, to import the model.
project_key: SOA

As adding/removing objects from a VDB results in filesystem operations of adding/removing indexes, this should result in a blocking of additional operations against the VDB.  If latency with the filesystem is large enough (for example, on a network filesystem) and no blocking is performed, multiple operations can be performed on the VDB resulting in the below exception:
!MESSAGE Unhandled event loop exception
!STACK 0
java.lang.ArrayIndexOutOfBoundsException: 0
	at org.teiid.designer.vdb.VdbModelEntry.synchronizeModelEntry(VdbModelEntry.java:435)
	at org.teiid.designer.vdb.Vdb.addModelEntry(Vdb.java:244)
	at com.metamatrix.modeler.internal.vdb.ui.editor.VdbEditor$25.selected(VdbEditor.java:1709)
	at com.metamatrix.ui.table.TableAndToolBar$2.run(TableAndToolBar.java:79)
	at org.eclipse.jface.action.Action.runWithEvent(Action.java:498)
	at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584)
	at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501)
	at org.eclipse.jface.action.ActionContributionItem$6.handleEvent(ActionContributionItem.java:452)
	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.Display.runDeferredEvents(Display.java:4066)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3657)
	at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2640)
	at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2604)
	at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2438)
	at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:671)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:664)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:115)
	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:369)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
	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:620)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:575)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1408)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1384)