Issues with video in Kubuntu 10.04

[pkaplan1]

The newest version of K/Ubuntu seems to be running the v6.13 of the ati 
display driver under xorg 7.5.

I've observed the following two behaviors (never a problem on older versions 
of K/Ubuntu) and my initial searches suggest that both result from this 
version of the driver.  Can anyone confirm?  Are there any fixes?

1.  Whenever I start an X session or switch from one virtual terminal to 
another on a machine with an ATI M7500 card, the screen is automatically 
dimmed to about 50% brightness (roughly the same as the window manager sets in 
powersaving mode).  I can increase the brightness using keyboard controls, but 
the window manager settings indicate that the screen is at maximum brightness.  
The behavior occurs with both KDE and LXDE

2.  If I have composting enabled in KDE and try to start a second X session on 
a different virtual terminal, the 2nd iteration of X hangs and I haven't yet 
found any error logs that are helpful.  Disabling composting fixes this.

Paul