tools -> registery clean up ->
there are three options which do diferent thigns
OLE Cleaner
Cleans unused and invalid Object Linking and Embedding entries.
Orphan File Reference Finder
Cleans registry entries that point to a non-existing file.
Automatic Registry Cleaner
Cleans what ever is possible to clean automatically.
NOTE: This can't detect as many obsolete entries as the human eye can by manually checking all of RegCleaner's sections, but on the other hand, this might find some things you can't.
and
Do Them All