Perhaps the installation has remnants of a previous subscription and needs to be cleaned up, but first check your system clock for accuracy, both time and timezone-wise.
If that is OK then try the following:
Uninstall all McAfee via Control Panel/Programs/Uninstall a Program (Add or Remove Programs in XP)
Run the MCPR cleanup tool listed under Useful Links at the top of this page and reboot.
Reinstall from the online account.