if the card is working on your friends computer when he tested it. then there has to be something on your pc that is causing the problem. your pc might be shutting down due to it overheating.
is the heatsync and fan working properly on your cpu?

It's not overheating, I opened it up and had a large fan blowing through it. When I gave it to my friend it was the whole desktop, and he had it over at his house. I don't think I mentioned this earlier, but it only shuts off on certain games. LFS, Halo Combat Evolved, and the old game 1nsane work fine. MW2, Grid and Combat Arms don't.

then it could be a software issue. have you checked your error log (control panel/admin tool/event viewer) to see if there is any crashes the system has logged?

Here are the errors-

under the system, there are a few warnings for tcpip and one for dhcp.

under application there's a warning for ASP .NET 4.0.30319.0 and a warning for WinMgmt.

use google to find out what these errors are. take your time and make sure you know what everything is. then you can decide what is causing your problem.

I'm pretty sure I've found the source of the problem. Apparently the card came overclocked right out of the box. I've read you have to get it under 680mhz for it to run right but I've got a problem. Look at the picture I've attached. CCC won't let you go under 725mhz. I'm currently looking around for an overclocking tool to try out and will post updates soon.

edit: ok, I found a program called rivatuner, turned it down to 680, turned agp down to 4x, and turned off fast write (which could've helped according to several sources I looked at). Nothing ended up helping it. I suspect because of the overclocking straight from the box, and that it worked fine for the first 2 weeks I had it then went crazy that ati fried my card because of the factory settings it came with. Is that a possibility?

no, when a factory oc's something, they tend to test it to make sure it's stable. are you using enough power? to be honest, i'm not sure what the problem is. all i can do is go through what i would do it i were in your position. if the card is still within warrenty, you might want to send it back to where you bought it. get a replacement/refund.
buy if there is nothing wrong with your card, you will end up having to pay the postage for it.
head over to the ATI forums, register there, and ask for help there. there is a better chance you will have more luck. if there is not a thread there that can help you, make one. but always make sure that you've used the search feature and made sure that there is not a similar thread.

Ok, I didn't know that. The way he said it made it sound like it was oc'd too far from the factory. I've got enough power, the requirement for the card was '300w recommended', and I've got a 500w psu. I'll try sending it back, and if I have to pay postage it will be worth getting my money back because the postage can't be more than I payed for the card. :P Thanks for sticking with my problem and all your recommendations dadge. I really appreciate it.