Have you tried a couple of these things:
Dump your cache files ( on your e: drive)
Make sure you network cable isn't connected.
Delete all stubbs files and directories.
Then try backing it up again.
For some reason, those things have worked for me in the past...I'm a TOTAL non-guru (at least I was able to install my chip, upgrade my drive, update my bios....and all that was thanks to the people on this board...)....
But Stubbs runs fine on my box (xbox v 1.0, xenium ice, evox 3865,) and I'm a tard.