Video problem: Every game crashes!

[Mursilis]

Until recently, my system was pretty stable. I'm running the following specs:

Abit KG7-RAID
Athlon XP 1700+
512 RAM
Radeon AIW 8500DV
Soundblaster Live
Win XP home
2 hard drives (not in a RAID array)
2 optical drives

Recently games have begun to lock up 1-20 minutes into the game. After it hangs, I have to reboot - Alt-Ctl-Del does nothing. I've tried various video drivers, with no change in the problem. I've also tried:

new RAM
new sound card
different video card (re-installed my old Radeon All-in-Wonder)
new power supply (Antec 400W)

This problem only occurs in games (MDK2, Warcraft 3, Rise of Nations, Battlefield 1942, Madden 2004, Age of Kings, UT, Quake 3, etc.), and the system is stable in Windows. These games used to work correctly, and I can't think of any specific change which triggered this problem. It began gradually, with WC3 locking up, then Rise of Nations, then the others.

Any tips or hints would be appreciated! Thanks in advance.

 

[Mursilis]

Anyone?

 

[McArra]

It sounds like overheating to me. Is the fan spinning?

 

[SneakyStuff]

Try a defrag or registry cleanup, Perhaps the problem does lie within your cooling tho, crack open your case and ensure everything is in order.

 

[Mursilis]

Thanks to everyone for the suggestions. I'll give a try to the disk defrag and reg cleanup. I don't think overheating is an issue because I'm not overclocking anything, and I've got 5 fans in the case, a two fan power-supply (Antec 400W), as well as fans on the CPU heatsink and v-card (of course). Also, the machine is in my basement, where it's very, very cold. The machine's loud, but cool, AFAIK.