Windows Backup: Error Code 0x81000001

I've been using the Backup tool that comes with Windows 7 for a good couple of months now, and its worked fine through various system reinstalls and testing and... yeah anyway.

I got a 2TB drive on Black Friday, and I've been attempting to do backups to it, only to get the above error code. Googling around leads to no apparently obvious solutions that I can see, including the "Run chkdsk /f" which also doesn't do anything to the C drive because it never appears to actually run at startup for whatever reason (it will say its starting, and then just boot into Windows, but I think that's a far more common problem from what I've seen).

The only thing I can see preventing it from completing is that I formatted the 2TB drive using a GUID partition table, my other 1.5TB external was formatted with a MBR table, and backups worked on that, but I haven't come across that as being an issue.

Any ideas?

 

I tried that the other night, it gets to 99% and then says it didn't complete successfully, which I find amusing.

 

Have you tried running the backup with the AV turned off? And I guess the ext. hard drive is NTFS formatted?

 

NTFS formatted yep, and I disabled everything from startup, but with the same result.