every time I install fc2 I get this problem and on different hardware even though it is supported. perhaps a bug...
you should also check the specs for your monitor. you will need to know the refresh, vsyn, hsynv rates. if you don't know, you can probably get the info from the manufacturer's website. and edit the /etc/X11/xorg.conf section
Code:
Section "Monitor"
Identifier "Monitor0"
VendorName "Monitor Vendor"
ModelName "Dell E770s"
DisplaySize 320 240
HorizSync 30.0 - 70.0
VertRefresh 50.0 - 160.0
Option "dpms"
EndSection
of course using your specs.