RUNAS and Backup

Every time I try and run Vista Home Premium Backup, I get the following
error:-

"The RUNAS command is not supported. You must run this program as the
logged-in user"

Has anyone any idea why this does this and how to stop it. I have used
Backup many times without any problem but the last time it was scheduled it
failed with this error and I have the same result if I try to run it
manually.

[diode]

I installed this to get a file off an old XP backup and now I get these errors. I am going to uninstall it and turn of the service it uses.