PineCone:
Thanks, I have fixed everything.
Do you mean you fixed the post (which I see is true) or you fixed your actual problem?
If you fixed your problem, what was your solution?
One thing that jumps out at me with the sender code is that it doesn't call Serial.begin(). Because of the nature of the Yun's USB serial port, the port may be functional without calling Serial.begin(), but perhaps some internal buffers of the Serial class aren't set up properly if Serial.begin() isn't called. If so, perhaps it eventually hits a point where any more data causes problems? (Just a wild guess - a stab in the dark.)