title: Mage.exe fails with "Unrecognized file type" during ClickOnce manual deployment
body: <p>We run <code>mage.exe</code> as part of a NAnt-powered ClickOnce deployment task of our back office desktop application, which contains mostly Windows Forms and a little of WPF. </p>
  
  <p>For one new developer, the following command is failing (some names changed for obfuscation...)</p>
  
  <p><code>mage/mage -Update "\\MyServer\Installs\QA\MyClient\Application Files\MyClientUI_4_44_0_1\MyClientUI.exe.manifest" -Name "MyClient QA" -Publisher WeCorp -Version 4.44.0.1 -UseManifestForTrust true</code></p>
  
  <p>(Note: the <code>mage.exe</code> file is in the relative subpath shown, all by itself in that folder...)</p>
  
  <p>For everyone else on the team, this exact command works fine, but for one of two new developers, if fails with:</p>
  
  <p><code>Unrecognized file type - "\\MyServer\Installs\QA\MyClient\Application Files\MyClientUI_4_44_0_1\MyClientUI.exe.manifest"</code></p>
  
  <p>Is there some machine-level configuration that affects what <code>mage.exe</code> considers to be a "recognized file"? </p>