A app. has a invalid uninstall info. The user try to uninstall it. ZU try also... But ZU doesn't say anything when it can't do that.
Why not a info to the user? "Uninstallation process failed. Would you like clean this program from the list and clean up its files (if found)?".
Here ZU can delete the files that are in "InstallDir" maybe - beyond invalid uninstall registry info.