Intro movies, the main menu, and in-game graphics all flicker rapidly.
System:
Vista 32 SP1
4 (3) gigs DDR800
e6400
p3d-based Mobo
Ati 4870x2
X-Fi
So far I've tried all 'Imaging Scaling' and 'DVI Settings' options/combinations in the Catalyst Control Center, have disabled AI (this has the additional effect of disabling the second GPU on X2 cards), and killed all driver-level FSAA/AA, but have seen no change.
Any thoughts or experiences from people using similar cards would be great. :) Thanks.

Have you tried playing with enabling/disabling Vsync?

Thanks, ghanz. Just tried out all Vsync options with no luck. However:
Disabling AI worked this time around. I've updated my drivers to 8.9 since I last posted, so it was presumably a driver issue.