I found a couple posts regarding this error on StackOverflow and posts on various forums. There doesn't seem to be any one cause or solution for this error.
So that it might help somebody else, below is the text of an email I sent to DevExpress regarding my experience with this error.
=== A month or two ago I installed an update to the CodeRush Express and the free Refactor products and it reset my Visual Studio settings.
This week I installed the Silverlight developer tools. When I tried to install the RIA Services, it failed with an error that something was missing, I don't remember what it was. Given the prior problem when I updated the DevEx products, I decided to do a complete reinstall of Visual Studio. I uninstalled Visual Studio and all related products and reinstalled. Afterwards, whenever I opened a website in VS, VS would close and the following error message was entered in the event log: ".NET Runtime version 2.0.50727.3082 - Fatal Execution Engine Error (7A035FC0) (80131506)".
Not finding a clear fix anywhere, I did another complete uninstall of Visual Studio and all related products, and started reinstalling and testing after each item. I installed everything else before the DevEx products: Visual Studio and SP1, the Silverlight 3 Tools, Expression Blend, Deep Zoom Composer, Silverlight 3 Toolkit and the RIA Services. After I installed CodeRush Express and Refactor! Free ASP.NET, everything was still working. After I installed Refactor! Free VB.NET, VS again started closing whenever a website was loaded and making the same event log entry.
After I uninstalled Refactor VB.NET, the problem went away.
The DevEx installs and the Microsoft Silverlight developer tools installs don't appear to be getting along together.