Video Issues

I am having problems with an ATI Radeon HD 2600 XT video card. There are vertical lines (stationary) in some colors, and diagonal lines (moving from top left to bottom right) in darker colors. It seems that when I change the contrast they go away and then come back. I have confirmed that it is not the monitor and it is not the cable. it is locale to the Mac Pro. There is some problem with the video card. I don't know wether it is drivers or if it is an hardware issue. To find out I am wondering if there is anyway to reinstall the firmware or drivers for the card. Please Help.