Hi there.
I have a similar problem ith a NANO-board. That is that when I run a program that sends out strings (regular intervals ~ 1sec) the program seems to halt after a while when I don't read the data.
The program flow is monitored by an activity-led (13) when the data is sent. When I plug the USB back in or read data the program resets (values are re-initialized!)
The problem is that the board is intended for stand-alone use and sometimes can be monitored for correct functioning.
Anyone an idea?