I have an ER-411 that was working continuously and performing normally for almost 2 years. Yesterday, I noticed that the chip powers its self on and off periodically. The period of each on/of is 168 seconds. (This particular chip comes with an LED that turns on when the chip is powered.) I have changed the power supply but I still get the same behaviour. It is appreciated if someone could explain the reason for this behaviour. (BTY the LED does not flicker when it is turned on.) Thanks.