I'm seeing word on the Microsoft forums, that uninstalling Silverlight using the MATS (Microsoft Automated Troubleshooting Service) is what actually fixes this (and then upgrade to Silverlight 5).
The posters say that a simple uninstall doesn't fix it, the MATS needs to be used. I don't know what this is (and not at computer to try) but will do it tonight.
Afterward, I will test this over the next week and report progress, as the problem is too intermittent to know for sure in one day.
Yesterday I turned off Microsoft Security Essentials in fear that that was causing the error. If only one single Microsoft developer would read these posts and review it from an application/developer perspective. I feel we're all shooting in the dark.
-Tres