Good read for Spektrum users.

Having owned four DX5e and one two DX6i and using both Orange and genuine Spektrum RX, I sometimes noticed the RX would blink when connecting a fresh battery adter the initial first flight of the day.  Now I know the answer.

http://www.rcpowers.com/community/threads/a-little-secret-about-hobbyking-orange-2-4-dsm2-rx.7149/

To avoid the blinking RX light, always turn off the TX and allow it to reset before plugging in a fresh battery.

AKA Brown out.