Monitor Display

You have tried a different monitor? Or that monitor on another PC? My last two distortion problems were simply dying displays . . .

Make sure that the monitor is correctly identified in display properties / settings /advanced.

If the monitor is incorrectly identified, it can be sent video signals and refresh rates that it cannot handle.

I would also check for updates for the mother board / chipset drivers.

One other possibility that I've experienced (inan office environment. Rearranged a users office (which placed a woking monitor in a different location). Started experiencing distortion problems (mainly color distortion). Finally discovered that the wall behind the monitor covered one of the main utility risers for the building (to include power). Electrical fields surrounding the power conduits were strong enough to cause distortion in the monitor.
Have you moved your monitor lately to a new location?

Un-shielded speakers (stereo, not computer) are the most likely cause.

Not sure where my head was, but after re-reading the question, I don't like my own answer above. If rebooting temporarily fixes the problem, then I suspect a temperature sensitive hardware failure. First I would try to beg, borrow or steal anothermonitor and see if has the same problem. If not, then it is probably time for a new monitor. (But first put the old monitor back and give it a second chance - I'm a Yankee and like to be SURE I have to spend money!) If the other monitor does the same thing, it is probably time for a new video adapter.

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