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It strikes me that your VertRefresh should be 60.. unless your flat panel can really do 50-75?

Manufacturers spec says:

VIDEO INPUT Analog RGB Analog (75 ohms, 0.7/1.0 Vp-p) Digital DVI-D (TMDS, 100 ohms) Frequency f h : 30~82kHz, f v : 50~75Hz

Hmm, just for grins try it at 60hz fixed, and see if that stabilizes it. To really fiddle about with it and optimize it, I'd still recommend xvidtune or advancemame's setup program to generate modelines. Once you have those set & working (and only those in your config) the variability should go away.

So it sounds like your panel has a DVI but the video card doesn't? Maybe I need to sell you my Geforce 4 ti4200 and buy a radeon :)

DB