Updated to 4.1 Pro, but says license invalid?

When launching Unity an error says that the license is invalid and i can either re-activate it or quit, when choosing the reactivation option i then enter my serial but again it says its invalid, so now im running the free version. Major problem is, i have my project releasing in 2 months and now have no way of working on it fully and with all the features...

Completely at a loss as to what to do, a friend said something about finding someone to borrow an activation file from? but i don't know if there's legal issues with that or something,

Any help greatly appreciated.

-Orion