nvidia 8600GT Graphics Problems???

Just purchased a new AMDx2 4400+ with a nvidia 8600GT videocard.The only program I have loaded is sw2007, but I seem to haveissueswith the video card slowing the whole system down. When themouseis over the model, the model will get horizontal bars goingthruit. You can still rotate and zoom just fine, I'm assuming itsanissue with the video card. The computer slows down quite abitafter using it for an hour. Any help is very muchappreciated.JasonSolidworksAdministration