Win 7 x64 and problems with ERUNT

I have, since loading Win 7 x64, not been able to use ERUNT to automatically
backup the Registry at startup. It appears that if you elect for the ERUNT
default configuration to save the 'backup' to %systemroot%\ERDNT the backup
will fail. However, I have since learned, (Google where else?) that if you
elect to save the backup to another folder it will succeed. In my case I
save the backup to a USB drive (P:\ERDNT) and 'autobackup' runs as it should
at startup.