digimesh serial port lockup

I am sending the transmit frame programmatically in a loop, api mode 2. If I don’t delay a few seconds between each transmit, the digimesh locks up and I have to cycle power on it. This is with 9600 baud. Has anyone else seen this?

Also, on receive, my mac (connected to the receiving digimesh) sometimes drops packets. I know the sender is ok because I get the status packet for the dropped packet. The two digimesh devices are only 3 feet apart. Has anyone else seen this?