After developing a WPF application without Source Control, I decided to add the solution to TFS.
After doing so whenever I opened the main window.xaml file in Design View Visual Studio would disappear and the following event would be logged in the Application Event log:
.NET Runtime version 2.0.50727.3053 - Fatal Execution Engine Error (7A035E00) (80131506)
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
Same issue, but without Power Commands installed. The only workaround I've been able to consistently use is to Clean/Rebuild the solution before opening ANY xaml file. If you can't get into your solution because the XAML is loading on start up, delete the suo.