The C4001 exception indicates a communication failure
between the iMQ broker and the iMQ client runtime.
There is a known bug in iMQ 2.0 broker that can cause
this type of exception on the client side. This bug
has already been fixed in the iMQ 2.0 SP1 (service
pack 1) release. It is available at -
http://www.iplanet.com/downloads/patches/5059.html