java.lang.NullPointerException - error

[doctorj]

I get this error in my java console in Netscape 4.61 on the web server which is running this app. It works in Netscape 4.x on other clients and it works in IE on the same server. Any ideas as to what would cause this?
Below is everything copied from my java console.

Stephen

Netscape Communications Corporation -- Java 1.1.5
Type '?' for options.
Symantec Java! ByteCode Compiler Version 210.065
Copyright (C) 1996-97 Symantec Corporation
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HURLnET's ISP Admin Started.
ISP Admin Version: 2.0
ISP Admin Date : Friday - March 26, 1999
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java.lang.NullPointerException
at sun.awt.windows.WToolkit.prepareScrImage(Compiled Code)
at sun.awt.windows.WToolkit.prepareImage(Compiled Code)
at java.awt.Component.prepareImage(Compiled Code)
at java.awt.Component.prepareImage(Compiled Code)
at ImageCanvas.<init>(Compiled Code)
at IspAdmin.drawScreen(Compiled Code)
at IspAdmin.init(Compiled Code)
* at netscape.applet.DerivedAppletFrame$InitAppletEvent.dispatch(Compiled Code)
at java.awt.EventDispatchThread$EventPump.dispatchEvents(Compiled Code)
at java.awt.EventDispatchThread.run(Compiled Code)
at netscape.applet.DerivedAppletFrame$AppletEventDispatchThread.run(Compiled Code)