Alright, some things to try.
I dont know what cleaner you used but one of the best, if not the best is CCleaner, this handy tool will clean your registry and cookies in seconds - [ame="http://www.filehippo.com/download_ccleaner/"]Download CCleaner 5.02.5101 - FileHippo.com[/ame]
Once its installed, open up the Exe and clean out your cookies first. Once thats done scan the registry (Look to the left, there should be a tab called Registry.
If that doesnt work, go to start > run > and type in your default Call of duty 4 directory, if the Activision/Call of duty folder is still there delete it, even if it IS just the folder and nothing else. (my default call of duty 4 directory is C:\program files\activison - Call of duty 4, yours might be different if you changed the default directory)
I cant really explain it right now, its late and my mind isnt working properly lol....Ill try to edit this tomorrow morning