Hi Ray,
what is the exact exception that you are getting?
check in the default trace file for the exception ID, and the relevant stack trace.
When exporting into PAR file - did you make sure that the name of the PAR file is exactly the same name as it should be (the name of the deployed application)?
Sometimes the export to PAR file changes the name of the PAR file, and then you have in your system the same application within two different PAR files - this of course causes problems.
Thanks & regards,
Michal Zilcha-Lang