Audio Streaming Glitches

I'm building a patch that streams audio over a network using jit.net.send and jit.net.recv.

The problem is that I keep getting glitches in the audio whenever I interact with the MAX interface. So if I change window focus, move a window, unlock a patch or sometimes even touch a number box. Sometimes it's just a one off glitch and sometimes it introduces a continous distortion into the signal that doesn't stop after finishing the interaction. It also happens sporadically at other times with no obvious cause.

This seems to happen on whichever machine I use (Windows Vista and XP so far), and on both sides of the network, but is absent if I use the loopback interface. The CPU load is around 13% so I don't think it's that, and it happens on even the simplest patch so I don't think it's that either. I also can't see any problem with the network - it's the only thing running over a dedicated router, I'm not getting errors about dropped packets and it also seems too closely linked to the GUI.

I've included two simple patches below where I have the problem. They're more or less taken straight from the help files......

I'm out of ideas on this so any help very much appreciated!