title: Applet: Java.lang.SecurityException: class "..."'s signer information does not match singer information of other classes in the same package
body: <p>I have an applet that will not load for 1 client who is running IE7 on Vista.</p>
  
  <p>The error is: </p>
  
  <pre><code>java.lang.SecurityException: class "com.arup.web.printing.WebPrintApplet"'s signer information does not match signer information of other classes in the same package.
  </code></pre>
  
  <p>The applet code is in a jar file named: <strong><em>WebPrintApplet.jar</em></strong> and it has a dependency on Sun's <strong><em>PdfRenderer.jar</em></strong>. I have signed both of the jar files with the same certificate and we are hosting the jar files from the same folder on our web server.</p>
  
  <p>I am at a loss for what could cause this issue in our case. My applet's code is all within the <code>com.arup.web.printing.WebPrintApplet</code> package and the entire jar file is signed. </p>
  
  <p>Any clues as to the issue and how to resolve it?</p>