Ive got exactly the same problem and the only way ive found to stop it is to switch it off.
In control panel of your computer
Double click Programs and features (or Add/Remove Programs)
Select McAfee WebAdvisor (or McAfee SiteAdvisor) from the list
Click Uninstall/Change or Remove
When prompted select only the checkbox next to SiteAdvisor (or McAfee WebAdvisor)
Click Uninstall (or Remove)
It will warn you that you are doing something drastic and the reason why, its up to you.
Im suprised McAfee cant solve this annoying problem.