This tool scans the system registry for seemingly invalid file and path references and displays them. Often after a few installations/un-installations of software the registry can become full of file/path references which point nowhere because the files have since been moved/deleted.

Decide which entries are invalid (unnecessary) and select them, then press the "Delete" button. It is usually safe to remove these entries, but only remove those you are certain about, and always make a backup of the registry before deleting anything from it. Some entries may seem like invalid file/path references but can actually be very important references.