Not sure what malwarebytes found.But it may have been something that screwed up your Mcafee security.If you go under usful links at the top of this page.You can run the MVT to see if everything is installed.IF not you may have to uninstall and reinstall.Run mvt i think it`s under tech support (useful links) then see what it says.If you need help reinstalling post back.Or you could do a tech support chat also under useful links.
I believe you should try to uninstall via Add/Remove programs and reboot the computer. Go to Useful Links at the top of this page and run the MCPR removal tool which will remove any remaining traces of McAfee that may be left behind that Add/Remove fail to completely remove and reboot again.
Then follow the instructions in this link and be sure to run the McAfee preinstall tool included in this link http://service.mcafee.com/faqdocument.aspx?id=TS100119 and see if your issue is finally resolved.
Let us know if you need further assistance.