Here's more information I forgot to mention.
The MDBs are returning a response using a typical temporary queue replyTo pattern.
I'm also getting a lot of deadlock error messages relating to the JBM_COUNTER table. JBM is apparently trying to increment some counter by doing a select followed by an update. The database I'm using is Sybase 15. I'm using an a transaction isolation level of READ_COMITTED and have changed the table to datarow locking.
I just noticed there's a JBM section. Sorry.
Could an admin move this thread to the JBM section please.
I'll just repost in the JBM section.