Probably a dumb question, but here goes...
You mention doing a restore with Registry Backup in a few ways: from Windows Recovery Environment, by going into Safe Mode and using the Command Line, by using a Live CD to boot a separate Operating System and do a file copy to replace the corrupt or unwanted registry files with the backup.
Ummmm...... does the lack of mentioning calling up cmd.exe from the Start Button and using the command line from there mean that trying to do that would NOT be successful or advisable? I know of course you'd have to re-boot right after you did that, but if for some reason the Windows copy of Registry Backup couldn't be called to do the restore, could a user use the command line from within Windows to run the restore program that's included with each set of backups, at C:\RegBackup\{Computername}... ??