Multiple Outlook PCs -1 user- Sync Prob.

We have an executive that has three PCs with the same userid/pw running Outlook 2000 to an Exch 2000 server. Are there any known problems with this senario? Occasionally gets lock-ups during dial-in (uses send/recv F9) while synch running and old messages that were deleted reappearing.
What happens if he disconnects during the sync processes – does part sync or is there a corrupt problem?