What does the client complain about? The prefix should not matter
Its a third party unsupported windows client that just crashes. I found other instances on newsgroups where PC client applications weren't well behaved in there parsing of messages. The aim was to change the prefix to see if this was causing the crash.
You can look at the message that we send when you enable DEBUG on the org.apache.axis category.
You can try to POST this message from a simple HTML form and modify it easily in a textarea