Thanks for replying. I think there is no problem with detection of the hardware. lspci shows me:
01:00.0 VGA compatible controller: ATI Technologies Inc NI Caicos \
[AMD RADEON HD 6450] (prog-if 00 [VGA controller])
Kernel driver in use: radeon
Let me describe what I'm seeing a bit more precisely.
1) No problem with the grub menu screen.
2) As soon as the graphical boot sequence starts (the animated logo thingy),
a fast, regular flickering or flashing starts.
3) This continues into the login screen, and continues once I'm logged on and
seeing my desktop. I'm able to access the menu that gives the suspend
option, but it's VERY hard on the eyes.
4) The flickering/flashing goes away totally after a suspend/resume.
I surmise that while the right drivers are being loaded for the video hardware, there's something wrong with the mode in which they're running at first (if that makes any sense). As I mentioned before, with FC 16 on the same box the video was fine from the start.