I have something similar but, only since I changed my gfx card :
before, ati 9600 pro 256mb AGP*8 ==> no freeze
after, ati HD3850 512mb AGP8* ==> freeze after 6 min, music still on, need to reset computer
M&B version 1.03
The problem is that all seem ok when I try to play others games ... (except 3850 kill 9600 pro in visual)
Others specs :
E2200 oc to 2750 ghz
2 gig ram 3200 DDR1
asrock 4coredual SATA R2