I'm having the strangest problem. I just built a new computer. Everything is working fine on a 1280x720 resolution, but when I go to a 1280x768 resolution every ten seconds or so the screen goes black for 1-2 seconds giving a message of "invalid format", then recovers the display. This repeats endlessly. I've updated nVidia drivers, and even tried beta drivers, that doesn't seem to be the problem. Only the 1280x768 resolution seems to be messed up. Any ideas? The monitor is just a 32'' LCD TV, it's detected as a generic non-pnp monitor. Thanks for help.
The 1280x768 resolution worked perfectly less than an hour ago on my previous machine. I've tried both inputs on the GTX 560 card. I might have located the problem. It looks like nvidia control panel is forcing a 85Hz onto the monitor when I need 60Hz... 1280x720 is the only resolution that doesn't flash in and out, and it's the only one that nVidia correctly runs at 60Hz; however I cannot seem to get it to stick with the 1280x768.