Missels right, most of this is speaker interference, or intereference from another monitor, or in some cases your computer itself

These little buggers put out all sorts of Electromagnetic/static/RF interference and it will effect most any monitor

All three of the monitors I've used lately (A GEM 15", a Mitsubishi 17 inch, and now a new Envision V770e flatscreen) all display a little slow-shake in the bottom left hand corner closest to my speaker system that has the amplifier built into it.

The same applies if you have a large subwoofer with an amplifier under your desk, even if they qre magnetically shielded, most aren't shielded against RF and other kinds of Chaotic interference.

Shoot, someone watching tv three apartments down, if there was just enough things in the apartment complex to reflect the RF interference, could actively fuzz your screen. Alas, this is a problem of modern living, less of modern technology.

You may still have this problem even with a newer monitor, only time I don't see the distortion is when I move the speakers further away, or boost the refresh into the 100hz+ range, which doesn't work at the resolution I use, so I just deal

Hope thats been educational