Client is running on windows XP (MQ client version 5.3) server is running on windows server 2003.
Ok so you're running on software where the .NET stuff was introduced with (did not specify the CSD) ...
To get MQ messages i am using dotnet amqmdnet assembly, version 1.0.0.3
The method Get(IBM.WMQ.MQMessage message, IBM.WMQ.MQGetMessageOptions gmo)
with messageoptions MQC.MQGMO_WAIT and messageOpt ...