Another issue related to my last post  VS 11 Beta issue: EnvDTE.Project.CodeModel returns null for a project just loaded without open documents is the following: the SolutionEvents.Opened event is not fired when you open a solution that was closed previously with all documents closed. Furthermore, the event is not firing when you open some document!.

The bug report is the following:

EnvDTE.SolutionEvents.Opened event not fired for a solution just loaded without open documents
https://connect.microsoft.com/VisualStudio/feedback/details/730000/envdte-solutionevents-opened-event-not-fired-for-a-solution-just-loaded-without-open-documents#details