very strange sockets problem

[Steel City Phantom]

im running bas 6.1, java 1.5 and jboss 4.  i have a servlet that 
interfaces with a bank over a socket connection.  pretty basic setup.  
everything works fine for the current two banks that we interface with.  
i am in the process of trying to bring up a third bank.  the socket 
opens correctly, transmitts the transaction correctly, the bank 
correctly receives it, processes it, and sends me a response.  the 
moment that the response hits my read buffer, the connection drops and i 
recieve no data.

i have eliminated all hardware in between the two systems.  i dumped the 
traffic with tcpdump and the machine does actually receive the data.  me 
and my team of developers are stumped, jboss support is stumped, i was 
wondering if any of you guys could think of something.

thanks
wilie