All of a sudden, my monitor (Sa...

All of a sudden, my monitor (Samsung-Samtron 56V) features--brightness, contrast, etc.,-- are appearing on the screen by themselves. They keep flickering on and off, lock and unlock ControlLock and do not go away even with repeated pressing of the exit button on the monitor. Keeping the exit button depressed even changes the display width, and contrast. So I have reinstalled the Operating system (XP). But to no avail. I had a host of viruses before reinstalling the OS. The viruses are gone. Now I have AVG free anti virus running. I have also tried downloading 3-4 antivirus' from the web and run them one after the other. But this monitor problem persists.
Need urgent help.