To the OP: What version of Office 2010 do you have installed? IF it is Professional Plus, even though you paid for it, it's more than likely one of the many pirated versions using MAK-activation, which, depending on when it was first activated, might well have worked. But, the leaked MAK keys are steadily being blacklisted by MS -- which means eventually, any copy using any of these keys is going to be Deactivated.
You should contact MS. Reporting a pirated version to them is sometimes sufficient for them to provide you a Genuine version -- but there are no promises.