AGP Problem?

I recently acquired a used computer from a friend with the Mach Speed K8M8MS mobo, reformatted the hard drive and installed Windows XP. I also have a brand new MSI NX6200 TD256H video card to go with it. To test the card, I started playing Day of Defeat, and it works well except for one major problem: After a little while of gameplay (5 or 10 minutes), the graphics totally mess up and it becomes impossible to do anything except open the task manager and end the process.

I'm pretty sure there is no problem with the card itself, as I have tried using three other older cards. I suspect a problem with the AGP slot or AGP driver. I have also tried reinstalling the game. As for Windows, other than the game and the drivers, I have a fresh install.

If you suggest updating any drivers, I would appreciate it if you told me exactly where they were. I've installed some, and I'm 98% sure they are the correct ones (got them from http://www.viaarena.com/default.aspx?PageID=420&OSID=1&CatID=1070). But even though it's not probable, I still could be wrong.

So yeah, I don't know if this is a bad mobo or what. Please help.