FULL PRODUCT VERSION :
java version "1.6.0"
Java(TM) SE Runtime Environment (build 1.6.0-b105)
Java HotSpot(TM) Client VM (build 1.6.0-b105, mixed mode, sharing)


ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Version 5.1.2600]


A DESCRIPTION OF THE PROBLEM :
Regression bug in 1.6.0, see bug no. 4918294 for JRE/JPI 1.4.2 and bug no. 2117857 for JRE/JPI 1.5:

When downloading a web based application containing java applets the java plugin occasionally throws a ConcurrentModificationException when the applet jar file has been updated at the web server. Application startup fails when the exception is thrown.


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
See Description Note of bug no. 4918294


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
See Description Note of bug no. 4918294
ACTUAL -
See Description Note of bug no. 4918294:

java.util.ConcurrentModificationException
at java.util.AbstractList$Itr.checkForComodification(Unknown Source)
at java.util.AbstractList$Itr.next(Unknown Source)
at com.sun.deploy.security.WIExplorerCertStore.getCertificates(Unknown Source)
at com.sun.deploy.security.TrustDecider.isAllPermissionGranted(Unknown Source)
at com.sun.deploy.security.TrustDecider.isAllPermissionGranted(Unknown Source)
at sun.plugin.security.PluginClassLoader.getPermissions(Unknown Source)
at java.security.SecureClassLoader.getProtectionDomain(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$000(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at sun.applet.AppletClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.applet.AppletClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.applet.AppletClassLoader.loadCode(Unknown Source)
at sun.applet.AppletPanel.createApplet(Unknown Source)
at sun.plugin.AppletViewer.createApplet(Unknown Source)
at sun.applet.AppletPanel.runLoader(Unknown Source)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)


ERROR MESSAGES/STACK TRACES THAT OCCUR :
See Description Note of bug no. 4918294

REPRODUCIBILITY :
This bug can be reproduced occasionally.

---------- BEGIN SOURCE ----------
See Description Note of bug no. 4918294
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
See Description Note of bug no. 4918294:
The current workaround involves clearing the plugin cache every time before starting the applet.