Unable to Backup Files with Error 800700B7

I am unable to backup anything in Windows Vista Ultimate. I am using the
Backup Files function in Vista to backup files to a local network location.
I can browse and find the location (e.g., "\\server\folder\") but when I
click <Next>, I get the error message…

The network share could not be accessed for the following reason:
Cannot create a file when that file already exists. (0x800700B7)
Please ensure that the network location is valid.

There was no file there already and this error has occurred from the very
first try. However, folders are being created in the selected folder with
names like {5C0AF261-393F-4FC6-9496-2576C5A3772E}. All help is appreciated.

[mgillespie]

Are you backing up to a NAS device?

I'm experiencing the same thing (failure of Vista backup using a Network
storage device). In my case, the storage device is a Cisco/Linksys NSLU2
with firmware version V2.3R63 (the latest version- Cisco hasn't updated
this for over a year). I *believe* this is using Samba 2.x, but I could
be wrong on that. I'm running Vista Ultimate edition, 64 bit, on an AMD
processor configuration.

I have tried making the change to Vista's local security policies to
use the (older) "Send LM & NTLM - Use NTLMv2 session security if
negotiated" setting, but this doesn't seem to make any difference with
backup. Whatever is going on, I seem to have full access to the NAS
file system with Vista for all other functions- just backup is failing
so far as I can tell.

And as noted, even backup itself seems to be able to access and create
directories on the NAS device.

same issue here, with my two iomega StorCenter 300 GB (firmware
v.1.27)

I'm unable to use built-in backup feature of Windows Vista Ultimate x64
SP2 on this NAS. Error 800700B7

Just found the answer! Use the username everyone and your admin password
for your NAS device. Everything works after that... I'm using Vista x64
and a WD Mybookworld NAS.