I'm using VS2003.
With this build (220) I can debug my unit tests but I've noticed this problem:
sometimes when I use the unit tests debugger the debug doesn't start, I can see the build goes successfully but the the "unit test runner" window doesn't hide showing me all the button in the toolbar disabled and the class icon in the hierarchy is set with the running gif.
The VS.NET tell me that no code was executing (the "Start" button is enabled)
Additionally in this state I can relaunch the unit test or the debug but with the same result as above.
Closing and restarting the ide fix the bug.
This was happened 3 times but I can reproduce it systematically.