Comcast are now offering the 2009 products so you may wish to uninstall, cleanup using the MCPR tool listed in my signature and then reinstall from the website.
This blank screen issue was a major problem with beta versions of IE8. If you have that then uninstall it and install the final release from Microsoft.
Whether or not you use IE, McAfee relies upon it.
Another thing that sometimes helps, assuming you have either IE7 or 8 installed (you should have 8 even if you don't use it) - go to IE Tools/Internet Options/Advanced and click the Reset button. OK any prompts and click Apply and OK.
Close and reopen IE and go to Tools/Manage Add-Ons and re-enable the add-ons.