McAfee Agent? Is the installed McAfee software Enterprise or Home edition? What is it listed as in Control Panel > Programs > Uninstall a Program?
Also is this Windows 7 SP1 and is the installed version of Internet Explorer 9 and not any beta version? This is important even if you use another browser.
Have you any other security software installed and/or any strange alerts otherwise indicating possible malware present?
It is listed as McAfee Anti Virus Plus Version: 11.0.543. The uninstall/Change option doesn't seem to work from control panel>programs and Features. The system had come with IE9 (64x) but as I was having problems with flash not working on it I had uninstalled it and am using IE8 which is working fine. The McAfee site advisor is working fine on both my browsers IE8 8.0.7601.17514 and chrome. I have Windows 7 Home Basic SP1.
I don't have any other security software installed other than windows bit defender which was there earlier too. And I'm not getting any strange alerts or messages.
64-bit systems have 2 Internet explorer versions, the 32-bit and the 64-bit versions. You should use the 32-bit one as most add-ons don't work well with the 64-bit one yet. Flash is only good on the 32-bit IE.
Please reinstall IE9 and make the 32-bit one the default (if you use IE) and hopefully the problem will go away.
Click this image of my Start-All Programs menu to enlarge if necessary to see what I mean:
I'm not sure only a technician could tell you exactly what happened by linking to your machine and collecting logs. If you want to contact Tecnical Support by phone or online chat, it's free and linked under Useful Links at the top of this page.
But first try the Virtual Technician. It can sometimes mend things that are broken: http://mvt.mcafee.com/