Unit Tests are failing on a "Build failed" in the Session window with no message providing a reason for failure in Visual Studios 2010

I had recently installed VS 2010 on my local machine, and cannot seem to get Resharper 5.1 and the unit tests to work correctly. Whenever I try and run Unit tests I get a "Build failed" with the test icon remaining gray, but with no info in the output window and no discernible reason why.

The Unit Tests run perfectly fine when doing a nant build.

Running a previous branch of the code on VS 2008 does not have this same issue as a result.

Any ideas?