We're excited to announce that we've fully migrated the Xbox Forums to their new home, here on the Microsoft Community forums!
As of today, going to forums.xbox.com will redirect you here to the Xbox area of the Community forums. We've moved all of your existing threads over so you can continue and start conversations with the new forums experience.
We sincerely appreciate the feedback you have provided over this transition and can't wait for you to check out the new Xbox Forums!
Well yeah your Gamertag can only be online at one place (Xbox or PC) at one time. It shouldn't of messed with your account though. The only thing it should of done is boot where ever you logged on to first (Xbox), when you logged in the second time (PC)