I would start by uninstalling the display adapter and the monitor in the Control Panel, System; and have Windows reinstall the drivers upon rebooting.
Another maintenance task to run is to Select Start, Run, and enter SFC /scannow. Noter that there is a space between SFC and /. A dialogue box will open advising that Windows is checking all required files. Another dialogue box may open asking for the Windows installation disk so that corrupted files may be repaired. Insert the Windows CD and select Retry from the options. This process will procee for about 20 minutes and repair any corrupted files in the protected files.
This should clean up any problems with system files and drivers. See if this helps.
Chris
September 2006