computer help PLEEEZ!!!

[texastechster3 (A)]

xp home
ATI 32 mb Rage Fury
600mb RAM
1.1 AMD

i've never had a prob w/ this computer, but now I've got a big one.  When launching SOME games, not MCM thank God, the puter is restarting.  The only change I've made was to download a couple of games via Torrent.  I got RISK II, an oldie, and it ran several times no problem.  now, when I try to start it, and another one I got, 4x4 Evo 2, i'm restarting. 

i've updated drivers, antivirus, verified there are no compatability probs.  What do you guys think?  what am I doing wrong???  thanks in advance........

[aaron.270 (A)]

One possible problem that comes to mind is that one of your games or recently installed software is not compatible with windows xp.  I had a old version of easy cd creator on my computer and whenever I shutdown my computer it restarted.  It reallly made me angry.  I would check any older software for compatibility issues with xp by using (insert favorite search engine here) for known issues with the software.