Two steps; registry entries and then leftover folders.
Whenever I use Revo, I also go into the "Advanced" settings for the registry and carefully tick only the bold entries in there. The bold entries are the ones that pertain to that particular software that I want to uninstall.
That means sometimes going down the registry tree and checking them, being very careful not to delete any un-bolded entries that might be right above the bolded ones. Depending upon the software installed (and how many registry entries it creates), it might be a time-consuming process.
I also delete any leftover folders it wants to leave behind by selecting all and then the delete button in that particular case.
Your registry could be damaged in some way. That's not Revo's fault but more something done as user error.