Civ4 problem, please help

[mazzz]

I just bought a ATI 9250, it works great when i am using my PC, but when I play Halo or Civ4 it works for about 5 minutes and then all of a sudden the sound stops and the screen says check plug in or something. It is inside the PCI port and the proper driver is installed. Please help

 

[crunch]

Post a screenshot of the error. Or the exact text.