Two iPads, One Wil Back Up, the Other not

[TheBigCheese]

I have a 32GB iPad 3 and my wife has a 16GB iPad 3' both WiFi. Recently, I could not backup my iPad to my Windows 8 PC. my wife's iPad backs up fine. I followed Apple's troubleshooting instructions and found I could backup my iPad using a different Windows account.

How can I clear things up so I can back up using my regular account?

Sync works on my account, by the way. The error message from iTunes is: iTunes could not back up the iPad because a session could not be started