First, welcome to Mobilitysite. Lots of good info and ppl here.
Second - It may be a memory issue in your computer or PDA/Smartphone. When the memory in my PDA was low it would lockup Outlook periodically. Once I cleaned up the memory it would work fine. Most of the time it was clearing out the messages on my PDA. I finally gave up have Outlook download messages. :exc:
Ps - I have the same version of Outlook, ActiveSync and OS (XP) as you do.