I experienced the same flicker problem and it is now solved, but I'm not 100% sure what solved it. The flicker went away after I turned off Enable Write Combining (display > Settings > Advanced > Troubleshoot) and rebooted. Flicker problem solved. To verify that Enable Write Combining was the cause, I turned Enable Write Combining back on and rebooted. And the flicker problem WAS STILL SOLVED. So, is Enable Write Combining the problem or does changing it and restarting have some side effect that cures the problem? Or is it something else I did that I don't realize. Anyway, if you're still experiencing the problem, Enable Write Combining (off) may be worth a shot. If turning it off solves the problem, I suggest turning it back on and testing again.
I don't know if anyone else has experienced this, but I've seen flicker resulting from using the Auto Colour effect.
I found the flicker to be caused on a number of machines by a poor combination of Directshow filters. For example, Nero SHowtime and Premiere do not well coexist. Uninstalling Nero instantly solved my problem. The problem is on Premiere's end, though. Using plain Graphedit to render a DV stream resulted in smooth, flicker-free video. One can only hope that Adobe finally addresses the problem in CS3.