Click Here to open a Kelly's Korner page.
On that page, scroll down to line 113 and in the left-hand column, click on "Enable" to download a small .reg file. Save it to the hard drive.
Once you have it downloaded, run it according to the directions at the top of the Kelly's Korner page.
If your antivirus objects to running the file, ignore it. The files from Kelly's Korner are safe.
The problem is often caused by malware; either spyware or a virus. Once you have Task Manager running again, you should do complete system scans with your antivirus and some spyware removal tools.