I am trying to understand what is creating this problem, I have a clone Mega 2560 with a sensor shield v2 and a number of sensors. My sensor test program will randomly resets / reboots where the bootloader restarts the program (i.e. pin 13 flashes) and the serial output on my bluetooth link shows the program has restarted. The system I am connecting to is Windows 7 64 bit, and it would appear that this only happens while the USB is connected, but I am not 100% sure on this. Is this a normal issue while running the IDE under Windows or have I got some other issue to track down?