I am running Windows 7 and I have never had this problem with CS 5. But every time I convert to a smart object and hit Smart Sharpen, my Photoshop freezes and I have to force stop the program. Can anybody help me resolve my problem, so I can sharpen without the program freezing?
Since Smart Sharpen now uses the GPU the suspicion falls on your display driver.
Since you have a Windows system you can visit the web site of the maker of your video card and download their latest display driver release for your hardware and OS version.