NullPointerException while loading an Applet at sun.misc.Launcher$2.run

I have observed this problem in 3 vista m/cs. (urti070.india.sun, my personal laptop and desktop)
This is not happening consistently. But some times due to this exception applet is not launching.

Here is the exception :
Exception in thread "Thread-17" java.lang.NullPointerException
at sun.misc.Launcher$2.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.misc.Launcher.getBootstrapClassPath(Unknown Source)
at java.lang.ClassLoader.getBootstrapClassPath(Unknown Source)
at java.lang.ClassLoader.getBootstrapResource(Unknown Source)
at java.lang.ClassLoader.getResource(Unknown Source)
at java.lang.ClassLoader.getResource(Unknown Source)
at java.lang.ClassLoader.getSystemResource(Unknown Source)
at java.lang.Class.getResource(Unknown Source)
at sun.plugin.util.AnimationPanel.loadImage(AnimationPanel.java:358)
at sun.plugin.util.AnimationPanel.initImages(AnimationPanel.java:386)
at sun.plugin.util.AnimationPanel.preloadResources(AnimationPanel.java:507)
at sun.plugin.util.AnimationPanel.doPaint(AnimationPanel.java:564)
at sun.plugin.util.AnimationPanel.run(AnimationPanel.java:1062)
at java.lang.Thread.run(Unknown Source)