Monitor..... No signal found

Everything loads and runs fine for a while, It's after thes screen saver comes on or when I start playing a game, Sims3 for example. The monitor will go black and the " No signal" banner comes up. I try to turn off and unplug the monitor then restart just that, I even went and pulled an lcd t.v. out of anouther room and ran it. did the same thing. The only way to get picture back is to restart the computer. I have taken the video card (NVIDIA GeForce 210) and cleaned it up with canned air. Nothing I have tried works. Could it be something in the setings or is it my vid card going to shyyt again( just put this one in back in March 10') Any suggestions are greatly appreciated.
Thank you