Error: 0x80070005 Access denied, back up failed

Hi
I tried using the backup feature on my vista lasptop for the first time and
received the above error message. i am the only user on the computer and
have administrator rights. Its an HP Presario V6000

The error message was accompanied by the following information:

the backup did not complete successfully
an error occured the following information might help you resolve the error
access is denied.
Error: 0x80070005 Access is denied Backup failed.

I was backingup some of the contents of the local disk (c) and had unchecked
the recovery disk.
In addition, before the backup began it asked for permission to format the
dvd i was backing up to. I gave this permission and now it seems the disk
is unusable for anything even although it is still empty. please excuse my
ignorance as i don't know alot about computers. Any advice would be
appreciated. TIA