Vista Full Back Up to Network Drive Requires User Name & Password?

I have a 3 computer home network, 2 desktops are Win XP Pro and notebook
is Vista Ultimate x 32 machine. Have administer rights with full
permissions on all 3 machines. One external Seagate 160 GB drive is the
network drive used as a backup. The drive is 40% full. All computers
and network drive are fully visable from each computer. No problem to
copy any file or folder to the back up drive from any machine. *::Now
the problem...::* When I attempt to do a ::_full_:: backup of the
notebook using Microsoft back up utility, to the external drive, I get
the dialog box telling I need a *login and password*.. Never had a log
in or password for anything. Can't get past this.
Tried to go the external drive to check if a password is possible and
there is no place for it. Tried to change the drive permissions but no
settings are retained. Tried to set up another user account on the Vista
machine with a password to access the user account, did not work. Tried
closing UAC and that did nothing.
Looking for some ideas...


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nevadaharv