Try running the Virtual Technician to see if it finds and fixes errors. http://mvt.mcafee.com/
If that doesn't help, go to Control Panel > Programs and uninstall McAfee.
Then run the MCPR cleanup tool, reboot.
Reinstall from your online account.
Note: If you have Family Protection and/or Anti-Theft installed the above can't be done as easily and you should contact Technical Support - linked under Useful Links at the top of this page, or for Anti-Theft only here (see Announcement at top of page): https://community.mcafee.com/community/home/anti-theft
Meanwhile ensure that your operating system is totally up to date, especially IE, evn if you don't use it.