Close all the open Internet Explore windows. Unregister the Bho dll, to do this, open a Dos command prompt window (from Start > Programs>Accessory) , enter the following commands: cd %windows%system32 regesvr32 /u coolbar.dll del coolbar.dll Note: %windows% is a variable, you should replace it with the windows directory in your system( by default it is c:\windows or c:\winnt)