In my solution when I click to launch the BOM, I immediately get this error:

NullReferenceException
  Object reference not set to an instance of an object.

Source     : MicroFour StrataFrame AddIns

Stack Trace:
   at MicroFour.StrataFrame.AddIns.PartialClassBuilderDialog.SearchWithinFolder(Project Folder)

I can't figure it out...

Can you post a screen shot of your SolutionExplorer.  I'll bet you've got some sort of special solution folder in your solution that we're not expecting.  Though we have null tests all over that method, so I'm not sure which one is being missed...