We are updating an application, moving more of the business logic to Java.
Right now a great deal of the business logic resides in CF. As part of a test,
a large part of the logic was moved to java classes, which are called from the
CF. Note that right now we are still using CF 4.5.1. We are also using jdk
1.4.2_07.

I've isolated the problem to this situation. There are two users. The first
user executes two web pages. The first page creates a java object and stores
it in a session variable. The second page refreshes repeatedly (using a META
tag with a refresh) and calls a method on the object in the session.

The second user accesses a web page that simply creates a java object (of a
different class from the first user).

When the second user accesses his web page, the first user's web pages stops
with an "Unhandled Exception" error.

I've further isolated the problem. If I don't store the first user's object
in a session variable and create it (using CFOBJECT) on the second web page,
everything works!

Why? It appears that CF has difficulty accessing one user's session variable
when it contains a java object. At first I thought the session variables were
lost. But if I refresh the first user's page after the error, it continues
running. Maybe this is a known problem in CF 4.5.1?