Screen saver reboots

Hi there, My problem is that when I select screen saver it reboots the computer. I recently installed tune-up.com and used the facility to alter the XP Welcome screen and I wonder if this is the cause or whether there is a known fault with this tune up software. Any help would be appreciated as I now can't change/get into screen saver.
I found the cause to be an update of ATI Radeon driver. I uninstalled and all appears to be normal again. I can get into screen saver without reboot. Thanks for suggestion.

 

I would use System Restore, and pick a Restore Point dated before the install of this stuff.