Open your browser, press Ctrl + Shift + Delete key combination and clear all cache, cookies and temporary Internet files. If it doesn't work, from your browser menu go to Options > Add-ons and disable the McAfee SiteAdvisor. After that, restart your browser and enable it again. If it still doesn't work, remove it and download and install the latest version available. In order to completely remove the utility, follow the steps below:
Google Chrome and other Chromium-based browsers: type chrome://extensions in the address bar. Press the thrash can icon next to the McAfee SiteAdvisor.
Firefox: press Shift+Ctrl+A (or open Tools → Add-ons). Press Disable next to the McAfee SiteAdvisor. If you can't find the toolbar in the Extensions tab, switch to the Plugins tab and look there.
Opera 12.x and older: press Ctrl+Shift+E (or press the Opera button → Extensions → Manage extensions) to open the Extensions menu. Press Uninstall next to the McAfee SiteAdvisor.
Internet Explorer: open Tools → Manage Add-ons. Select the McAfee SiteAdvisor and press Disable.