Please make sure you have the latest version of Registry Reviver.

Registry Reviver finds and fixes the errors. Some programs unfortunately might recreate the same invalid entries that were removed in the first scan and Registry Reviver will therefore find them again in your system. For example, when a program is executed, it may create files and place entries into the Registry that reference these files. When the program is shutting down, it may remove these files from your hard drive but not the entries that reference these files from your Registry, thus creating invalid entries.
There is no need to be worried though as just a small number of errors may reappear after being removed by Registry Reviver. To get a rid of the errors you will need to find the program that is recreating them.