If you are running Windows Vista or Windows 7 with UAC enabled and Visual Studio set to Run as Administrator and you try to open a Solution File through Windows Explorer, Visual Studio will not open. If you check the “Choose default program” for SLN files you will see that is set to use Microsoft Visual Studio Version Selector, which is the source of the problem. What I think is happening is that the version selector recognizes the right program to open, but since it is not running in elevated trust (Run as Admin) it doesn’t have enough permissions to...