PROBLEM

One of the first things that went wrong after upgrading to Fedora 10 was the UI screen was unreadable / undescernable.  The screen was entirely messed up and though the keyboard worked fine, it wasn't easy to discern the UI windows from the shades of red, yellow, blue, green etc grany dots that showed up.  In my case, I've solved this by lowering the video resolution in the below manner.  I have the ATI Radeo 9600 card.

SOLUTION

Here is how to change the video resolution on your system.

1. At the UI login screen hit CTRL-ALT-F2 to switch to a ready terminal login screen.
2. cd /etc/X11/
3. vi xorg.conf
4. I had the Modes item below like this with highest resolution listed as 1280×1024:
   Modes    "1280×1024" "1280×960" "1152×864" "1024×768" "832×624" "800×600" "720×400" "640×480"
5. Change above to the below to lower the maximum resolution allowed:
                   Modes    "1152×864" "1024×768" "832×624" "800×600" "720×400" "640×480"
   #               Modes    "1280×1024" "1280×960" "1152×864" "1024×768" "832×624" "800×600" "720×400" "640×480"
6. Type :wq <enter> to save the file.
7. Type $ init 1 at the console to go to single user mode. 
8. Once in single user mode (verify using runlevel) type $ init 5.
9. Your screen should now be fixed for you.

There after you could try to use these Graphics and Video: Changing the graphics/video resolution with xrandr instructions here to test the various resolutions Fedora 10+ can now handle once you are in the UI.