Cannot serialize session attribute

[Ramon Misho]

Hello iBatis people:

I am using Eclipse Version: 3.0.0 and Tomcat 5.0.19.

I edit a java file (in the Eclipse), and click on the 'Save' button. The 
'Reloading" starts as expected.   However, very often (but not all the time), I 
get the following error messages although they have no impact on the compiling 
process.  

                Cannot serialize session attribute myfileBean for session 
A2F0ED8D3C199E076B84EB3CF792C6FD
                ..................etc
                
The 'myfileBean' is the name of one of my JAVA files.   The strange thing is 
that when this error is generated, I am usually working with another JAVA file.

Any ideas?

Thanks.
Ramon