If you’re using Visual Studio 2012 with ReSharper on a 64-bit version of Windows and get these messages when trying to debug a test, this is a known issue with Microsoft VS2012 and not ReSharper (so don’t go blaming the guys at Jetbrains!).
Even though there have been several updates for VS2012, this issue still hasn’t been fixed. However there is a simple workaround which will get you up and running again. For each of your test projects, go to project Properties > Build and change Platform target to x86.
Now build the test projects and try again. This time it will let you debug your tests as normal.