This is strange...I've tested several games including UT2003,NWN,Warcraft 3 and the flickering has been there more or less depending on the game,but today i've tested the Call of duty demo and the flickering was gone!
The game is a little dark, but i looked for a long time and it wasn't there.
Since RoachMojo didn't detected the flickering with Tron 2.0 maybe this is somekind of driver issue after all.
Maybe some other people could try these games out and see if it's gone for them too.
If its dark, and at fast FPS, then your eyes cant see the flicker but its still there.
Its like that for me playing UT2K3... at 1600x1200 my fps varies a bit depending on where i am..... in a dark area with not much detail @ 80fps i can barely see the flicker if at all.... but once i move into a bright area and with more detail @ 50 fps the flicker stands out much more.
P4 2.26 1GB rdram4200, MSI GF-FX5900U256