Complete PC Backup could not start

Hi,
Since the last successful Complete PC Backup on my 500GB USB drive on
October 11th, any new attempts were unsuccessful. After pressing "Back up
now" in the "Backup Status and Configuration, the second window "Where do you
want to save the backup"does not appear, and instead, after a minute or two,
the following message appeared "The backup application could not start due to
an internal error. Server execution failed (0x80080005). Please check your
system configuration and try again".
I do not know where to look to solve the problem. Any suggestions?
In the meantime I've installed the SP1, but that did not help.

Thanks!