I've just upgraded to the latest stable Xamarin/Vs2015 (I can't get the version as VS won't display it due to crashes) and I get the above error.
The VS log shows:
586 Begin package load [XamarinShellPackage]
587 LegacySitePackage failed for package [XamarinShellPackage]Source: 'mscorlib' Description: Unable to load one or more of the requested types.
588 SetSite failed for package XamarinShellPackage
589 End package load [XamarinShellPackage]
Any ideas on how to fix it?
I'm on VS2015, Windows7.