FULL PRODUCT VERSION :
java version "1.6.0_03"
Java(TM) SE Runtime Environment (build 1.6.0_03-b05)
Java HotSpot(TM) Client VM (build 1.6.0_03-b05, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Windows Vista

EXTRA RELEVANT SYSTEM CONFIGURATION :
With Mozilla browsers

A DESCRIPTION OF THE PROBLEM :
When opening an online Java game Java tries to update the following registry key even though the process does not have permissions to do so and then crashes the browser.
HKEY_LOCAL_MACHINE\SOFTWARE\mozilla.org\Mozilla
Name = CurrentVersion
Value = value of the current Gecko

Mozilla Firefox as of the 2.0.0.8 release includes an application manifest which prevents registry virtualization on Vista which is how Java was able to successfully write to the registry previously.

Additional details can be found at
https://bugzilla.mozilla.org/show_bug.cgi?id=400467
and
http://crash-stats.mozilla.com/report/index/6c604e57-806a-11dc-b3fb-001a4bd43ed6?date=2007-10-22-06

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
With Windows Vista in its default configuration (e.g. UAC turned on using an administrator account) open a web page with a Java game
http://www.flyordie.com/games/online/games.html?lang=en&game=8Ball&room=801&rs=1
Select the button to play the game as a guest

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Can play the game
ACTUAL -
Browser appears to freeze and then eventually crashes
Crash report
http://crash-stats.mozilla.com/report/index/6c604e57-806a-11dc-b3fb-001a4bd43ed6?date=2007-10-22-06

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
Grant Full Access permission for authenticated users to
HKEY_LOCAL_MACHINE\SOFTWARE\mozilla.org\Mozilla
To clarify:
The original problem is because plugin fails reading from HKLM\Software\mozilla.org\Mozilla\CurrentVersion on Vista and therefore it could not load.

This is due to new change in FF install engine in which a manifest is used to override virtualization by Vista. Therefore, when FF is installed on vista, it fails to write to HKLM\Software\mozilla.org\Mozilla\CurrentVersion location.

Plugin tries to read this registry to determine what plugin adapter lib to load and therefore the symptom is plugin fails to load on Vista for FF2.0.0.8 and later.

At least no one from deployment team was able to reproduce the crash scenario.