Fast User Switching bug

[GusTheSadGeek]

Hi, I have a 9800XT and XP pro SP2.
When I try to switch users with ATItool running the PC resets.
Also when I try to shut the PC down the screen freezes says "saving your settings".

I have tried using AtiTrayTool as well and this does the same.

Has anyone else expirienced this ?
It did the same before I installed SP2.

[GusTheSadGeek]

I was underclocking my card 100/150 to keep the case temps down when I wasn't playing games.

If I only underclock it to 200/200 then the fast user switch works fine.