Are you using Internet Explorer 9 Beta by any chance, or any other beta browser? They are not supported so you would have to uninstall them for McAfee to function properly.
If you are not using a beta browser please open Internet Explorer anyway and go to Tools/Internet Options/Advanced and click Reset, Apply and OK.
Close and reopen I.E. and go to Tools/Manage Add-ons and re-enable the add-ons.
It should work now.
These instructions apply to IE8 which you should be using or at least have installed if you use another type of browser as the default, or IE7.
Could you please let us know if you got the issue resolved ???
McAfee Online Community Moderator