When doing major upgrades or downgrades such as 8 to 8.1 or back it's wise to completely uninstall McAfee during the process as it may interfere with the process and will almost certainly become corrupted anyway.
Uninstall McAfee via Control Panel > Programs and Features
Then run the MCPR cleanup tool and reboot
Reinstall from your online account.
Moved to General Discussion sub-forum.
Thank you very much,i managed to reinstall my internet security quickly,thanks again
That's great. All the best ;-)