When loading/reloading applets, "netscape.javascript.JSException: Unknown name" exception is displayed in the Java Console. Applets are still functioned fine and can be interacted with w/o any problem. This issue only observed with Internet Explorer using Sun JREs,
NOT with Internet Explorer using MS VM or Firexfox using Sun JREs.
 
These following applets display the problem:

popcap - Mummy maze, Atomica,Rocket Mania, Typer shark
Yahoo - Pop & Drop, Bounce Out, Diamond Mine, TipTop
pogo- Book worm

Steps to reproduce: (popcap - Mummy maze applet )
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1) Install Mustang build into the test system
2) Browse http://www.popcap.com
3) Click 'ALL GANES'
4) Click 'MUMMY MAZE'

"netscape.javascript.JSException: Unknown name" exception displayed in Java console when loading/reloading the applet.