Check your machines for spyware using the free versions of these two tools and let them delete anything they find:
http://www.superantispyware.com/superantispywarefreevspro.htmlhttp://www.malwarebytes.org/mbam.phpAs McAfee relies on Internet Explorer working correctly please go to IE/Tools/Internet Options/Advanced and click the Reset button, then Apply and OK. Close and re-open IE and re-enable the add-ons under Tools/Manage Add-ons.
On the machine with IE8 , I trust by RC you mean IE8 final version? Treat that the same way. If it isn't the final version then uninstall it and reinstall the final version or go with IE7.
Go to this link for Comcast McAfee downloads:
http://security.comcast.net/There is 24/7 Technical Support available through the link at top left of this page or in my signature.