Crash on [OM.UI 578] The Direct Reference supplied invalid

[joako]

I have 1 mailbox that crashes when SmartCache is used. I have tried Outlook 2003 and 2007 Windows XP and Windows 7. I can export the mailbox all day long and import it to a fresh new mailbox and no matter what after outlook syncs the SmartCache it crashes. I notice the following log entry each time this happens:

WARNING Remote Client (U/I Access ) 07.31.10 22:02:26
[OM.UI 578] The Direct Reference supplied is invalid
User Name: Jane Done / sclx/CN=Doe, Jane
<- ual_GetMsgId
-> ual_GetAckId
<- ual_GetAckId
-> mapi_SyncRelFlags
<- mapi_SyncRelFlags
-> mapi_SyncCompFlags
<- mapi_SyncCompFlags
<- ual_BuildListEntry
-> ct_ReadNextContentRec
<- ct_ReadNextContentRec
-> ct_GetCtnerLastCRec
<- ct_GetCtnerLastCRec
<- ual_UpdateAnyList
<- ual_ContentNumForDI
<- /build/11.4.6/src/lib/ual/ual_dref.c:218[101,578]
<- /build/11.4.6/src/lib/ual/ual_dref.c:247[101,578]

What steps can be taken to insure that Outlook does not crash when the SmartCache is used? I already made sure there are no add-ons enabled and I can load other Scalix mailboxes on the machines in question.