Cannot sign out of TFS in Visual Studio.

I have two microsoft logins with two different emails and was using one to sign in to visualstudio.com team foundation from Visual Studio 2010. This was working but somewhere along the line it has picked up my other microsoft login (I might have used it to sign into SkyDrive or Azure) and now when I connect to TFS it uses that instead. If I click Sign Out to try and use the original it does a bunch of requests but stays logged in as that account.

I've totally cleared my credentials vault so it's not getting it from there. I've cleared the AppData\Local\Microsoft\Team Foundation caches. I've done a registry search for the second email address and removed the identities that were under Office 15, I've restarted Windows after doing all that and it STILL picks up the wrong login.

So now I've used fiddler to try and figure out what is going on when I attempt to log out.

The sequence of calls is roughly:

https://tfsprodch1acs01.accesscontrol.windows.net/v2/wsfederation?wa=wsignin1.0

https://myproject.visualstudio.com/Services/v1.0/Registration.asmx

The last of which gets a 404 and then some calls to LocationService and CatalogService

I suspect the problem is with the call to login.live.com because it has a cookie which seems to be linking my two accounts. The cookie starts with