It's not your video card; it's the monitor. My old Daytek 17" had that problem. It would turn kinda bluish until I jiggled the connection. The connection was on fucking tight, and I even tightened it with pliers.
Eventually, though, the blueness started happening more and more often, and I had to resort to banging on the side of the monitor to fix it.
I was able to fix it by opening the monitor and soldering wires together, bypassing the connection on teh back of the monitor. Of course, the monitor was never really the same after that, because all of the colours were kinda off a bit.
Don't know how to fix it other than performing surgery, or just resorting to buying a new monitor. I recommend moving your computer so you don't nudge any wires anymore.