After the last updates on Fedora 16 (x64) I have been suffering from really bad screen flicker.
My PC has these specs. Specifically a “ASUS GeForce GTS 450 Direct CU Overclocked 1GB” Graphics card driving a BenQ T2200HD.
The symptoms are that when I alt+tabbed between windows the screen corrupted(Black artifacts) and flickered.
I think I have an answer (at least it appears to be working) which is to install the Proprietary NVIDIA Driver as instructed here
This may be an option for you if you notice the same thing on F16.