A few minutes ago I got the following error:
Error 1 API restriction: The assembly ‘file:///C:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\PublicAssemblies\Microsoft.VisualStudio.QualityTools.UnitTestFramework.dll’ has already loaded from a different location. It cannot be loaded from a new location within the same appdomain.
It was weird.
To solve it I removed the two unit testing framework dlls from my project (see below) restarted Vs then re addeded them back.
<Reference Include=”Microsoft.VisualStudio.QualityTools.UnitTestFramework, Version=126.96.36.199, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL” />
<Reference Include=”Microsoft.VisualStudio.TeamSystem.Data.UnitTesting, Version=188.8.131.52, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a” />
That seemed to work.