System is an Asus a8n-sli deluxe w/amd 3700, geforce 6600gt, 4mb ram, 550w pwr sply - W7 home premium 64. W7 has been installed for almost a year but this problem is recent. The pc is my wife's and is used for web surfing, photo viewing and video playback. It is not a gaming machine. The geforce 6600gt card is no longer able to use the nvidia drivers. In device manager it displays the yellow exclamation point and the message is that windows stopped the driver because it had problems. The display seems to be fine. If I select the Windows wddm version of the nvidia driver, the warning/alert goes away. At first I thought it was a card problem. The card was old so I bought a new evga geforce 9600gso to replace the 6600gt. When I install the 9600gso, I get no display at all. If I put the 6600gt back in, I get a display and have no issues as long as the windows display driver is selected. If I attempt to reinstall the nvidia driver, I get a problem alert in device manager. Also, the nvidia control panel is inoperative. I have uninstalled nvidia and gone into safe mode to run Drive Sweep. I then attempted to install the 9600gso but still get no display. I put the 9600gso in a different computer and it works fine. Any suggestions on how I might get nvidia operating? Also, any suggestions on how I might get the 9600gso card working?