i've flown my cx2 in my house with my fiancee on the phone in the next room with no issues. i've never heard of any inerference problems with these digital systems. that is thier big selling point. i have had glitching issues with other r/c vehicles (am and fm) and none of them went completely dead instantly. usually its a loss of control, like a car steering to the right on it's own. i'd check my electrical connections if my heli died and fell out of the sky. also, you mentioned you were on your 3rd or 4th pack. did you let it cool down between flights? you may have had a heat issue in the 4 in 1. just a thought.