Look around for any mention of HDMI CEC or LG's name "SIMPLINK" and disable it.
Read http://www.avsforum.com/forum/167-plasma-flat-panel-displays/1264176-disabling-lg-s-simplink.html for a similar discussion.
LG 50PJ50 Annoying POP-UP AV2 "New external device connected. Do you want to ENJOY this? YES - NO "
There are no devices connected. Have not experienced issues in 4 years since it's purchase.
It remains persistent and will not stop blinking in sporadically no matter what has been attempted to resolve this kind of issue.
I think maybe the remote infrared is possibly corrupted from other external means.