F10 -> F11 X server problem with /dev/fb0

[Peter J. Stieber]

I just upgraded an x86_64 Fedora 10 system to Fedora 11.  Now when I run 
startx I get the following complaint.

(EE) open /dev/fb0: No such file or directory

Then the screen output says...

Fatal server error:
Detected GPU lockup

My Fedora 10 system was using the Fedora Xvfb package to perform offline 
processing.  I stopped that server, but I'm still getting the error.

$ lspci
...
01:00.0 VGA compatible controller: nVidia Corporation NV44
[GeForce 6200 LE] (rev a1)
...

I'm wondering how to go about fixing this.  I know this probably isn't 
enough to "go on", but just ask, and I'll provide more information.

Pete