Monitor problems, or is it my software? PLEASE HELP

[magpie01]

Ok, I recently purchased a used Daewoo cmc2000m monitor, and my video card is an NVIDIA geforce 6800. The problem I have been having is that when I exit from full-screen games, the monitor seems to crash. The screen becomes a pixilated, wavering, non-full screen mess, and a loud clicking sound comes from the upper rear of the monitor. When the monitor is turned off and then back on, the problem persists. When I switch to a different monitor (which works perfectly), the monitor does not work, and I get a "the monitor is working, but the computer output is outside of rendering range" message. I have to reboot the system with the old monitor plugged in for the problem to resolve itself, and everything goes back to normal when I switch cables back to the Daewoo. If I just reboot with the Daewoo plugged in, the problem continues. . . I have already replaced the monitor cable, as the old one had pins missing, but that hasn’t helped. I ran the direct draw test from dxdiag, and on the old monitor the test work ok, but on the Daewoo, the problem happens after the full screen bouncing square test. I don’t know how to fix this, please help!