I had this same problem some weeks back. Not sure how it happened, but it appears that my display driver got corrupted somehow.
You need to update/replace the display driver. Drivers are available at
www.nvidia.com.
By the way, updating the driver was not fun. First off, you have to start the machine in safe mode to even see the display. Furthermore, the driver has a nasty habit of re-installing itself (the bad/corrupt one) as soon as it is uninstalled. Finally, the driver itself had some installation problems; kept telling me that I had the wrong hardware (which I most definitely did not) - just try several times.
Have fun. By the by, even with the upgrade I am having some problems (which is how I came across your problem). Can't seem to get around an error/lockup with "Medal of Honor - Allied Assult".