That's a zero.

http://answers.microsoft.com/en-us/windows/forum/windows_vista-performance/0x810000ed-error-while-taking-backup-error-backup/8d44f039-ece5-4a26-885c-8533577d7334

It's a very rare error according to a search. We know that Norton and Kapersky and maybe other security apps as well as virus damage cause such issues.
Bob