As you haven't given a any details about your system I can only assume that you have a new machine with Vista. It looks like this is a known conflict issue and the fix is below. The underlined piece is the important bit. Games/graphics programs apparently use the Ati service so you would have to start it manually if you needed it or the second bit below in Italics will start the service later automatically if you want the convenience.
Start vista in safemode.
Open services.msc. (Start - RUN)
Set the Ati External Event Utility in manual mode.
Open your startup folder in your start menu with "explore with all users".
In this folder make a file named AtiExternalServiceStart.bat or a name you prefer.
edit this file and add the following line:
net start Ati External Event Utility
This will start the Ati service later so it will not conflict with vista
'Reboot'