Personal build - Fetching files to fetch destination ... java.lang.IllegalArgumentException

Hello,

we have a client who has the following set up: JTS ver. 4.0.2, RTC-BuildSystem-Toolkit-AIX-4.0.2 and RTC-scmTools-AIX-4.0.2 (command line build, Jazz build engine ).
They received an error message when trying to execute personal builds for the following test case:
Stream A- workspace A
Stream B- workspace B
Stream B was branched away from Stream A
Building from the workspace A works fine
Switch to workspace B and build for stream B works fine
Switch back to workspace A the error occurs: "

2014-03-24 14:51:10 [Jazz build engine] Should build occur?
2014-03-24 14:51:10 [Jazz build engine] Yes: Always build a user initiated request.
2014-03-24 14:51:10 [Jazz build engine] Invoking pre-build participant "com.ibm.team.build.jazzscm"
2014-03-24 14:51:16 [Jazz build engine] Fetching files to fetch destination "/nsework/iccbld/personal_builds" ...
java.lang.IllegalArgumentException
    at com.ibm.team.internal.repository.rcp.dbhm.DiskBackedHashMap$Entry.<init>(DiskBackedHashMap.java:924)
    at com.ibm.team.internal.repository.rcp.dbhm.CachedDiskBackedHashMap$CachedEntry.<init>(CachedDiskBackedHashMap.java:263)
    at com.ibm.team.internal.repository.rcp.dbhm.CachedDiskBackedHashMap.createEntry(CachedDiskBackedHashMap.java:206)
    at com.ibm.team.internal.repository.rcp.dbhm.DiskBackedHashMap.getEntry(DiskBackedHashMap.java:534)
    at com.ibm.team.internal.repository.rcp.dbhm.CachedDiskBackedHashMap.getEntry(CachedDiskBackedHashMap.java:136)
    at com.ibm.team.internal.repository.rcp.dbhm.DiskBackedHashMap.getEntry(DiskBackedHashMap.java:491)
    at com.ibm.team.internal.repository.rcp.dbhm.CachedDiskBackedHashMap.getEntry(CachedDiskBackedHashMap.java:109)
    at com.ibm.team.internal.repository.rcp.dbhm.DiskBackedHashMap.get(DiskBackedHashMap.java:155)
    at com.ibm.team.filesystem.client.internal.LockableMap$1.get(LockableMap.java:71)
    at com.ibm.team.filesystem.client.internal.core.SharingMetadata2.getFileItemInfo(SharingMetadata2.java:2355)
    at com.ibm.team.filesystem.client.internal.core.SharingMetadata2.getFileItemInfo(SharingMetadata2.java:3131)
    at com.ibm.team.filesystem.client.internal.copyfileareas.CopyFileAreaStore.getItemInfo(CopyFileAreaStore.java:1388)
    at com.ibm.team.filesystem.client.internal.Shareable.getFileItemInfo(Shareable.java:646)
    at com.ibm.team.filesystem.client.internal.Shareable.getFileItemInfo(Shareable.java:635)
    at com.ibm.team.filesystem.client.internal.Shareable$1$1.visit(Shareable.java:268)
    at com.ibm.team.filesystem.client.internal.Shareable.visit(Shareable.java:616)
    at com.ibm.team.filesystem.client.internal.Shareable.access$0(Shareable.java:600)
    at com.ibm.team.filesystem.client.internal.Shareable$1.visit(Shareable.java:260)
    at com.ibm.team.filesystem.client.internal.core.SharingMetadata2.acceptAll(SharingMetadata2.java:1871)
    at com.ibm.team.filesystem.client.internal.core.SharingMetadata2.acceptAll(SharingMetadata2.java:1883)
    at com.ibm.team.filesystem.client.internal.core.SharingMetadata2.acceptAll(SharingMetadata2.java:1883)
    at com.ibm.team.filesystem.client.internal.core.SharingMetadata2.acceptAll(SharingMetadata2.java:1883)
    at com.ibm.team.filesystem.client.internal.core.SharingMetadata2.acceptAll(SharingMetadata2.java:1883)
    at com.ibm.team.filesystem.client.internal.core.SharingMetadata2.accept(SharingMetadata2.java:1845)
    at com.ibm.team.filesystem.client.internal.copyfileareas.CopyFileAreaStore.accept(CopyFileAreaStore.java:2406)
    at com.ibm.team.filesystem.client.internal.Shareable.accept(Shareable.java:306)
    at com.ibm.team.filesystem.client.internal.localchanges.LocalChangeTracker.computePendingChanges(LocalChangeTracker.java:735)
    at com.ibm.team.filesystem.client.internal.localchanges.LocalChangeManager.refreshSynchronously(LocalChangeManager.java:356)
    at com.ibm.team.filesystem.client.internal.localchanges.LocalChangeManager.doRefresh(LocalChangeManager.java:394)
    at com.ibm.team.filesystem.client.internal.localchanges.LocalChangeManager.refreshChanges(LocalChangeManager.java:640)
    at com.ibm.team.filesystem.client.internal.load.MergeLoadMutator.load(MergeLoadMutator.java:435)
    at com.ibm.team.filesystem.client.internal.load.MergeLoadMutator.execute(MergeLoadMutator.java:291)
    at com.ibm.team.filesystem.client.internal.operations.FileSystemOperation.run(FileSystemOperation.java:89)
    at com.ibm.team.filesystem.client.internal.operations.LoadOperation.load(LoadOperation.java:939)
    at com.ibm.team.filesystem.client.internal.operations.LoadOperation$1.run(LoadOperation.java:593)
    at com.ibm.team.filesystem.rcp.core.internal.resources.ResourceSharingManager$1.run(ResourceSharingManager.java:76)
    at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:1800)
    at com.ibm.team.filesystem.rcp.core.internal.resources.ResourceSharingManager.runWithinFileSystemLock(ResourceSharingManager.java:88)
    at com.ibm.team.filesystem.client.internal.operations.FileSystemOperation.runWithinFileSystemLock(FileSystemOperation.java:164)
    at com.ibm.team.filesystem.client.internal.operations.FileSystemOperation.runWithinFileSystemLock(FileSystemOperation.java:144)
    at com.ibm.team.filesystem.client.internal.operations.LoadOperation.execute(LoadOperation.java:624)
    at com.ibm.team.filesystem.client.internal.operations.FileSystemOperation.run(FileSystemOperation.java:89)
    at com.ibm.team.build.internal.scm.SourceControlUtility.updateFileCopyArea(SourceControlUtility.java:619)
    at com.ibm.team.build.internal.engine.JazzScmPreBuildParticipant.preBuild(JazzScmPreBuildParticipant.java:238)
    at com.ibm.team.build.internal.engine.BuildLoop.invokePreBuildParticipants(BuildLoop.java:844)
    at com.ibm.team.build.internal.engine.BuildLoop$2.run(BuildLoop.java:650)
    at java.lang.Thread.run(Thread.java:595)

Does anybody have an idea why this happens?

thank you,
Zica