machine freezing up on me

[dacmb5]

I recently had my machine in the shop for a motherboard replacement and a new power supply. I got the machine back and it worked great with the ati agp card that was in there when I had them replace the motherboard. However after I knew the machine was going to be just fine I decided to put back in my old Creative Blaster Riva TNT card. Now what happens is that every time I boot up the machine it will load all the way up like normal but once it's been fully loaded, it seems that it will just lock up on its own. This happens anywhere from about a minute after it's been booted to about 5 minutes after. I can shut it off and reboot it and the same thing happens again. I'm a bit stumped. I have an ibm compatible PC from Nutrend, celeron 400, 64 megs of ram and the new motherboard installed was a Biostar M6TBA.
Any help would be appreciated. Thanks.

[SysOpt]

TNT cards run hot. You might have a heat problem. I'd try either using a different graphics card, or adding a fan to your case (or the card itself).

[Underclocked]

My guess is that you did not fully uninstall the drivers for the previous vid card.