You probably tried to update using Autoupdates. The first thing Microsoft installs this way is Windows Genuine Advantage (WGA)
This software checks if your Windows is genuine or pirated. If pirated you wont be able to use Windows unless you purchase genuine CD from a Microsoft retailer. In the message, the contact phone numbers of the MS retailers are given. If you think, you bought genuine Windows, contact Microsoft and explain.
More information on MS website:http://support.microsoft.com/gp/contactwga