Incorrect background color handling and resulting exception.
Here are the steps the customer submitted, using jre 1.5.14, and he's got the 14 hardcoded in the testcase. I duplicated this under 16 as well, making the appropriate change to the java source. I followed his steps and duplicated the behavior he claims.

I followed the steps under java 1.6.0 update 7 and could not duplicate the behavior.

a. Install the jre 1.5.14 or jdk 1.5.15
a. Put the files applet.html and InJava5.class in the document root of a
webserver.
b. Load applet.html file in Internet Explorer. I have used IE 7.
c. The applet has a button labeled "Execute Javascript". On clicking the
button, the background colour of the html page is changed to light green
colour.
d. Now type another URL [ e.g. www.google.com] in the address bar and load
the page.
e. Hit the "Back" button of the browser to navigate to the previous page that
has the applet.
f. Now click on the "execute Javascript" button. The colour of the background
page does not change. The following exception is shown in the Java console : Exception in thread "AWT-EventQueue-2" netscape.javascript.JSException:
Failure to evaluate self.document.bgColor='#CCFFCC'
at sun.plugin.javascript.ocx.JSObject.eval(Unknown Source)
at InJava5.actionPerformed(InJava5.java:18)
at java.awt.Button.processActionEvent(Unknown Source)
at java.awt.Button.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)