OK this is one I\'ve been trying to figure out for a few days now. We have an application on Windows Phone 7 where phones join a multicast group and then send and receive me
I notice you use the loopback. I think it means that when you send a message from your client you will receive the message you sent also. This means your receive handler will fire. It has the effect of clearing the receive buffer in a seemingly unthreadsafe fashion. Try putting some try catch in your receive method and see if anything untoward is happening but you might instead just not use the shared receive buffer in any case.