Outlook does not update – Exchange issue or other bug?

User issue:
When he is offline (PC shut down) any mail sent during that time is not replicated / synchronized to his local outlook.
The mails are visible on his blackberry, and when logging in to webmail, the ‘missing’ mails are there.

I have tried re installing office 2007, redone the user profile, but still – outlook does not update 🙁

User is on fully patched Windows XP with office 2007, and connected with Exchange 2010