Gazza,
I am having a similar problem with B/U on Vista.

For the last 8 weeks or so, I have my computer set for an automatic backup
every Sunday evening at 7pm. It was successful for the first 4 weeks and
then I get the message:
"Backup did not complete successfully. Incorrect function: 0x80070001"
This is the 4th week I receive this error message. Do you understand what
this error number means. It is similar to your error except for the last
digit.
Edward kelly

"Gazza" wrote:

> This is quite amazing. After 5 months of using the in-built backup facility,
> Vista suddenly decides that it is not going to be helpful anymore. Everytime
> I attempt a backup I am getting a a 0x80070005 error. This is stupid. I have
> over 1Tb of storage available to me so I shouldn't be getting this error. I
> have also attempted to backup to another external drive and the same problem.
>
> Easy to solve I thought. I have spent the last 6 days on the Net trying to
> find a solution and there isn't one. I have chkdsk the drives, run utility
> programes and everything is saying the drives are ok.
>
> MS don't have an answer. Does anyone know what to do?