Outlook 2007 Drag and Drop

I have one user in my whole domain having a issue with drag and drop.  He is using outlook 2007 SP2 connected to exchange 2003.  We also have a document management system called Interwoven filesite also integrated in the outlook.  This particular user also has at least 3 PST archive files connected to his Outlook.  When he tries to drag and drop from inbox it generally works the first time.  After the initial drag and drop the second time he gets the message "outlook cannot move the items. the item cannot be moved".  If i close outlook and reopen it, i can drag and drop 1 time before it happens again.  We originally thought it was a filesite problem but we started reading tons of post about drag and drop being broken int Outlook 2007 SP2.  Anyone please help me please.