Well, if you are like me, you updated to the ATI 11.5 Catalyst drivers and are now experiencing weird mouse lag at the corners of your screen. Here is what I did to fix the problem. I simply turned off the mouse shadow.
Fix ATI Drivers 11.5 Mouse Lag
This might not work for everyone, but until ATI fixes their driver, it is something easy to try.
Go to your Control Panel.
Click on “Mouse.”
Go to the “Pointers” tab and uncheck the box that says “Enable pointer shadow.” Press OK, and hopefully the problem is fixed!
I would also recommend installing this additional hotfix, 11.5b that ATI released.