I assume you posted more than this and the forum did not post the rest.
This error from what I read is usually caused by a corrupt install of Mcafee either the network connection was flakey or files were deleted or installed badly. Also having another AV installed can be a factor as all must be uninstalled usually by their own removal tool before installing McAfee..
My suggestion is to full uninstall the program (McAfee) as per
How to remove McAfee
and reinstall Mcafee from your account.
Prior to the reinstall it is a good idea to run
http://download.mcafee.com/products/mvt/tools/Preinstall/consumer/Pre-Install_Tool.exe