Normally I would tell you to contact Technical Support by phone, it's free and available through Useful Links at the top of this page, but that isn't open until Monday in your area but you could try the Online Chat if you like.
Try the following first:
First check your system clock for accuracy, both time and timezone-wise.
Uninstall the software in the normal way via Control Panel > Porgrams > Uninstall a Program (Vista/Windows 7) or Add or Remove Programs (XP)
Run the MCPR cleanup tool listed under Useful Links at the top of this page to remove any spurious leftovers and reboot.
Reinstall your software from your online account.
If all that fails, as I said, try support or at least post more information on your operating system and service pack details and what version of Internet Explorer is installed, whether or not you use it.