We have been tracking what appeared to be a weird but in the rx library for the last several weeks.   After some period of time a server would respond to a client with a last packet in a call.  The client would respond by sending an ACK and then terminating the call.   The client would create a new call and issue a request to the server.  The server would appear to have ignored the previous ACK and begin resending the last message of the previous call.   The client no longer believing the previous calls exists would ignore the duplicate messages but it would also *never* resend the first packet of the new call.  This deadlock situation would remain essentially forever. 

After pulling our hair out for several weeks we discovered that the hardware clock on the machine was set to the year 2015.  ntpupdate was reseting the clock to the correct time.  The reason the client wasn't resending the new call packet was because the resend timer was set to expire ten years from now.   I wonder if the server will still be there by the time the resend takes place.  :-D