hen it is not
possible to load the test and NUnit gives an error message.

<li><p>If multiple assemblies are being run at the same time, NUnit first
determines the runtime under which each assembly was built. The highest version 
is then selected for the entire group, and rules 1 through 3 are applied.
</ol>

<p><b>Note:</b> For versions 2.5.4 and 2.5.5, automatic runtime selection only
works in the Gui runner. Use the /framework option to select the appropriate
runtime under the Console runner.

<h3>Overri