title: That assembly does not allow partially trusted callers although the zone is fully trusted
body: <p>Since yesterday, I receive a security exception when I want to run a unit-test from within VS.NET 2008.
  The error goes like this:</p>
  
  <pre><code>SecurityException: that assembly does not allow partially trusted callers
  ... 
  The assembly that failed was : file:///S:/MyProject/MyAssembly.dll
  </code></pre>
  
  <p>The S: drive is a mapped drive which points to a physical location on my disk.</p>
  
  <p>What I find very strange, is that this used to work for months previously.  I mean, I did this all the time.
  In order to get this to work, I 've created a new security zone with the caspol utility in order to give this S: network share drive FullTrust.
  In other words, when I run </p>
  
  <pre><code>caspol -m -lg
  </code></pre>
  
  <p>I see this (I removed the other zones for the sake of brevity):</p>
  
  <pre><code>1.2.  Zone - Intranet: LocalIntranet
     1.2.1.  All code: Same site Web
     1.2.2.  All code: Same directory FileIO - 'Read, PathDiscovery'
     1.2.3.  Url - file://R:/*: FullTrust
     1.2.4.  Url - file://S:/*: FullTrust
     1.2.5.  Url - file:///S:/*: FullTrust
  </code></pre>
  
  <p>I've added the 1.2.5 zone just recently because the error that was given, mentionned file:///s:/.... </p>
  
  <p>Any ideas ?</p>
  
  <p>Could it be that this has something to do with the installation of VS.NET 2010 or the .NET Framework version 4.0 ?</p>