In NT, some keys are inaccessible by default for reading/changing even for administrator.
Some keys are permitted to read but not permitted to change. So, Undo/Redo functions don't work with such keys.
To change key permissions, use Regedt32, however, you must have appropriate privileges, of course.
It is possible to use logfile while scanning. If logfile is used, all messages are saved into logfile instead of being displayed on screen.
Logfile can be specified on External Editor & Logfile tab in the program Settings.