"Hkey_classes_Root" could mean something is screwed in the Windows registry
(the database that holds all the wondows settings)
You probably need someone who knows what they are doing to look at your PC.
If you have access to another PC, which i guess you must have to have started this thread, it might be worth doing a search on google for the name of the software
plus keywrods including "remove" and/or "Hkey_classes_Root" etc to see if someone has been there before.
Hope that helps a little bit.