We have an issue moving a .NET client app from Windows XP to Windows 7, connected to a WIndows 2003 server. The client loose connection to the server, and this seems to be something related to changes in underlying ping system. It seems the server side MSMQ (3.X) which is on Windows 2003 is expecting a ping that is not anymore provided by the Windows 7 client (MSMQ 4.X) Any help is welcome.
Try setting HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSMQ\Parameters\Security\EnablePingService to 1.