Have you tryed to reset the monitor to the default setting, Via the menu on the monitor itself. (Buttons on many are out-of-sight, just under the bottom front edge.)
It could be the drivers have somehow been corrupted and need to be reloaded/updated.
Unplug the power from the monitor and take a close look at the connections, especially the cable between the monitor and the computer. Is there any "play" or movement in the connector-housing where it enters the computer-enclosure or monitor-cabinet?
(Stressed or broken connectors can be replaced.)
And while its unplugged if you see the "Deguassing" switch, press and hold for several seconds. (It can't hurt, but is more likely to help "color-banding" issues.)
If you recently changed resolutions, you might want to run system-restore to a prior time to get the older settings.
Hope this can help.
