The beta bits have expired!
Problem is that when working with MVC, you cannot do this (since there's no *.aspx files!). So I used to add a dummy aspx file and use that to choose my browser. Since then all was well, but recently I received the following message:
Solution:
Goto: %localappdata%\Microsoft\VisualStudio\10.0\Extensions and delete the folder named: "Clarius Consulting", then re-download the extension and all should be well.
Hope this helps someone else if they've run into the same problem as I.
~ Steve