Before chucking your monitor away and buying a new one just make sure the symtoms you describe are not being caused by interference from some electrical or magnetic source. I have lost count of the times at work and elsewhere when people claim they're monitor is behaving strangly and its been found to be due to some environmental issue.
Try the monitor in a different room/location - just to be sure.
Try the monitor in a different room/location - just to be sure.