I am getting crash to desk top issues when I try to run AH2, any windows media files, and a couple other programs.  The screen goes quickly to a blue screen and then it reboots.  
After reboot, it says windows has recovered from a serious issue.  Says to update Bios.  but it also mentions a memory issue.  Computer is a 
Abit IP35 Pro LGA 775 Intel P35
Intel core 2 E8400 3.0 Ghz
4 meg Corsair DDR2 RAM
768 MEg 8800GTX vid card
running XP
Bodhi,
I have just experienced the same problem as you have.  About a week ago my system started acting up exactly the same as yours.  I thought it may be software and restored my HD from an image from a month ago.  After a bit the blue screen and reboot happened again and several more times.  
I had built my system in March using Crucial Ballistix RAM.  A month or so ago, I wanted to add 2 more GB of the same type but when I went to Newegg, the reviews really slammed the Crucial RAM so I held off buying it. Many failures happening within a few months of installation.  Ah ha, a light comes on.  I replaced my RAM with some Corsair and so far no reboots, everything fine.  Try replacing your RAM, it worked for me.
Salute,
BeDee