Firefox 6 crashes with (most recent) Java

[Per Anton Rønning]

The problem listed in the subject line seems to be widespread. Svereal 
people report this problem on various discussion lists.
As soon as Firefox tries to start a plugin, it breaks down with a 
message "this is embarrasing" etc. I have not yet found any fix that 
seems to work. I tried to install Firefox 5 instead of 6 to see if the 
problem is a ver. 6 problem, but now it does not pick up the Java plugin
(does not appear in the Tools/Add-ons list.) So it cannot be enabled.
I have created a symlink to 
usr/java/jre1.6.0._27/plugin/i386/ns7/libjavaplugin_oji.so,
both in /opt and (created by myself) /opt/plugins.
Does anyone have a suggestion as to what will fix this problem?

Best regards
Per Anton Rønning