Applet won't load for a second since JRE 6 update 21

Question

My applet loads the first time but not the second unless I turn off Caching in the Java Control Panel and delete the cache and temp internet files. The Exception is as follows :
java.lang.ArrayIndexOutOfBoundsException: 0
     at com.sun.deploy.security.CPCallbackHandler$ChildElement.<init>(Unknown Source)
     at com.sun.deploy.security.CPCallbackHandler$ChildCallback.openClassPathElement(Unknown Source)
     at com.sun.deploy.security.DeployURLClassPath$JarLoader.getJarFile(Unknown Source)
     at com.sun.deploy.security.DeployURLClassPath$JarLoader.access$800(Unknown Source)
     at com.sun.deploy.security.DeployURLClassPath$JarLoader$1.run(Unknown Source)
     at java.security.AccessController.doPrivileged(Native Method)
     at com.sun.deploy.security.DeployURLClassPath$JarLoader.ensureOpen(Unknown Source)
     at com.sun.deploy.security.DeployURLClassPath$JarLoader.<init>(Unknown Source)
     at com.sun.deploy.security.DeployURLClassPath$3.run(Unknown Source)
     at java.security.AccessController.doPrivileged(Native Method)
     at com.sun.deploy.security.DeployURLClassPath.getLoader(Unknown Source)
     at com.sun.deploy.security.DeployURLClassPath.getLoader(Unknown Source)
     at com.sun.deploy.security.DeployURLClassPath.getResource(Unknown Source)
     at sun.plugin2.applet.Plugin2ClassLoader$2.run(Unknown Source)
     at java.security.AccessController.doPrivileged(Native Method)
     at sun.plugin2.applet.Plugin2ClassLoader.findClassHelper(Unknown Source)
     at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
     at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
     at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
     at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
     at java.lang.ClassLoader.loadClass(Unknown Source)
     at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source)
     at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source)
     at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
     at java.lang.Thread.run(Unknown Source)
Exception: java.lang.ArrayIndexOutOfBoundsException: 0
Any ideas what is happening?
Thanks Mark.

Answer 1

EJP wrote:
'this.document' is a predefined variable that defines the URL source of the current page. If you are referring to the predefined variable that provides access to the Document Object Model then I believe you are mistaken, that is 'window.document' or just 'document'.
EJP wrote:
Your name either conflicts with that or is getting confused with it somewhere.The 'document' variable is a parent of the window object e.g. 'window.document' but my variable has the context of 'this'. That means 'this.document.URL' returns 'undefined' instead of the URL for the current page.
JavaScript is also case sensitive so 'document.URL' is not the same as 'Document.URL', the last of which returns 'undefined'.
If Java relealy was confusing my variable with the predfined one then I would expect the same behaviour if I were to use differnt variations of the variable. However the follwoing JavaScript doesnt affect the Applet in anyway:
<script type="text/javascript" language="javascript">
    //this.Document = 'string'; // Remove this line to get it to work again
    this.document = 'string';
    document = 'string';
    Document = 'string';            
</script>For some strange reason it only affects the Applet when 'this.Document' is used. Why would Java be affected in this way in the first instance? Even setting the 'scriptable' parameter to false doesn’t help:
<param name="scriptable" value="false">Are there any other settings I am not aware of that could maybe prevent Java from loooking at the JavaScript?
EJP wrote:
Use another name.As I mentioned in my original post this is not easily done, I can edit the source code on my own site but the code still remains unchanged on the Mootools JavaScript Framework website.
Thanks