I have recently upgraded to VS2010 Premium and Resharper 5.1.3000.12. Its test runner will now not execute MS Tests.
The dialog shows up but nothing happens.
Well, look like Resharper 6 does not have the issue.
http://confluence.jetbrains.net/display/ReSharper/ReSharper+6.0+Nightly+Builds
I am using build #2150 on 09 May 2011, and now the tests run as expected.