When Registry First Aid is correcting registry entries it creates a temporary backup file in system temporary folder. Perhaps, there're problems with temporary file. Please empty temporary folder before running Registry First Aid:
1. Click to the Start Menu -> Run... , type %temp% in the box and click OK. This will open temporary folder in explorer window. Delete unnecessary files.
2. Reboot your system.
Please also be sure that you close any other applications when you run Registry First Aid. Scanning the registry and hard drives takes a lot
of resources and CPU power.