IE9 has this setting, implying IE9 has GPU acceleration. But I don't
think IE8 has this. You would place a tick in the box at the top,
to stop using the GPU.
http://cdn4.digitaltrends.com/wp-content/uploads/2010/09/gpu_acceleration.jpg
I am out of other suggestions, why, from a hardware point of view, the
screen would be "unstable" when running IE8.
If you capture the screen, with a screen capture utility, does the
"instability" still appear in the captured image ? That would be
a check for a hardware issue of some sort. If a screen capture appears
normal, but the actual screen does not appear normal, then it could be
a hardware problem.
Paul