Created attachment 495975 [details]
logs that might be helpful (from both boxes)

Description of problem:
After installation of Fedora (which boots in fallback mode). I run updates to the latest Gnome-* packages in the fedora/update-testing repos as of the date of this writing.  I then install graphic drivers for nvidia, making sure vesa/drm is not loaded. Selinux does not throw any gnome-session-c* errors as per https://bugzilla.redhat.com/show_bug.cgi?id=694918.
I reboot and GDM loads just fine. After logging in, Gnome-shell seems to load normally, but then none of the buttons work.  The Screen appears frozen but it's not, because the mouse works and ALT+F2,'r' still reloads the shell -- though there is no UI display for the keystroke activity.  After the reload, the situation is still the same.  Mouse is working, keyboard is working, but Gnome-shell is NOT showing anything. The only way out is CTRL+ALT+F2 and the terminal.

Version-Release number of selected component (if applicable):
gnome-shell-3.0.1-1.fc15.x86_64

How reproducible:
Got two PCs frozen at the moment, so I'd say its replicable

Steps to Reproduce:
1. Download Fedora Beta, make a USB installer or burn a Live CD
2. Boot it up (mine starts and freezes with USB-2, USB-5 statements). Another system passed this stage but could only display a rainbow coloured noise pattern (and that's as far as that could go).
3. If any of the situation above happens, reboot the media with 'BASIC VIDEO'
4. In 'Basic Video' the Installer runs at fallback mode.
5. Run the installation.
6. After installation the system still runs fallback
7. Update the system (yum update) then reboot.  This should get the latest Kernel in the repos
8. Install rpmfusion repo and get nvidia drivers installed (using akmod-nvidia)
9. after installation reboot.  The system will not display GDM so I drop to level 3
10. Make sure nouveau/vesa drivers aren't loading (blacklisting), recreate initramfs and run nvidia-xconfig.
11. Reboot
12. The Computer will boot normally, and will start GDM.
13. After GDM, login 
14. Gnome-shell seem to start normally but then the buttons don't respond. Keystroke are accepted an implemented, mouse works but the Shell is not
  
Actual results:
See decription above

Expected results:
A working Shell. I expected to see a working activities hot corner, to see the calender balloon, to access user menu balloon etc.  I see only the top bar but its frozen

Additional info:
Both systems have nVidia GeForce 7300/7200 Graphics Card.  One has a Quad-core CPU while the other runs Core-2-Duo.  RAM is 8GB on the first and 4GB on the latter.  Using a generic USB keyboard and Mouse.