The problem is that IBM uses its own jvm to compile
jsp and run java applications . Therefore it's not your jvm that causes the problem but the one from IBM Websphere.
As an example if you develop a java using jdk 1.5, it wont work under Websphere even if you have the latestJVM on your computer.
The (awful) solution woulb be to recompile JForum classes using Websphere's Jdk........
[originally posted on jforum.net by rayool]