Created attachment 360480 [details]
Screenshot of a problem

Description of problem:
Fast user switching fails on G70.

Fast user switching feature stops working after some usage, producing
only white rectangle instead of rectangular users list on screen.

Version-Release number of selected component (if applicable):
 xorg-x11-drv-nouveau-1.0.0.15.8.20090904git2b5ec6a.fc12
  (All system, X packages as provided on testday-20090909 x86_64 LiveCD.)

How reproducible:
Failed three times in a row

Steps to Reproduce:
1. Boot from aforementioned LiveCD
2. Create two user accounts(for example user1 and user2)
3. Switch to user1 and after that, to user2
4. Switch between these two users one or more times
  
Actual results:
White rectangle instead of users list

Expected results:
Users list

Additional info:
This bug doesn't make the whole system to hang up and
although I wasn't able to switch user via GUI, it was possible
for me to switch to the second VT and log in.