Short and sweet, I had Visual SVN both and AnkhSVN installed. After uninstalling both the problem went away.

I was using Visual SVN until the trial ran out. I’m on a clients PC so I can’t install my own copy (boo!) so I tried Ankh…soon after both where installed I started getting the error.

I did not try just uninstalling Visual and leaving Ankh…I guess I should have.