For some reason, whenever I set my refresh rate to 70 or 75hz (Regardless of Resolution, from 640x480 to 1600x1200) the screen flickers and shakes a little. But at 60hz everything is fine (Other than the fact that having a refresh rate in sync with the room's lighting hurts the eyes) I'm using a Viewsonic G810 21" screen with a ATI XPert 128 16 Megs (PCI) under Windows XP with the WinXP drivers from ATI. I just tested switching back to 1152x864 @ 85hz and it's fine but on a 21" screen, I'd rather use a higher res. Is there a reason why it does that only at those refresh rates? And what's the cheapest way to fix it (Is it a VGA Cable shielding problem or something)?