Comment 25 for bug 602761

Just a post for anyone still following this: We ended up just forcing the nunit-console and nunit-gui to run on the .NET Framework 4.0 as suggested by Charlie above. This can be done by the following (since it didn't seem to already be posted in this thread):

1. Open each app.config file in the text editor of your choice (we did nunit.exe, nunit-x86.exe, nunit-console.exe nunit-console-x86.exe)
2. Right below the configuration append the following:
  <startup>
     <supportedRuntime version="v4.0.30319"/>
  </startup>
3. Save the file and restart Nunit

Note that this will force nunit to run with the .net framework v4.0.30319 all the time, for us this isn't a big deal as we have separate build environment for each version of the .net framework on which we deploy against.