When I open my solution, I get a dialog with this warning. The solution (one web app, one class project) builds without errors.
How can I determine what properties are causing the problem, and resolve the error?
I just fixed a similar issue with a VS2010 solution with 35 projects... The cause was a duplicated
GlobalSection(TeamFoundationVersionControl)
section in the solution file. I closed the solution, removed the duplicate GlobalSection(TeamFoundationVersionControl) config and reloaded the solution and the warning message was gone.
If this is not the issue for you, considering you only have 2 projects I would ditch the busted solution file, create a fresh solution and re-add your two projects...