Let me put my two cents in. I fly Spektrum DSM2 and DSMX and have for my years in the hobby. My club flies at an airport and during a period of time we were putting planes in almost every weekend. The plane would lose signal and either do aerobatics, fly straight, or simply nose in. Our safety officer blamed it on bad piloting, but when you see your plane just start looping until it lands in the trees and you show everybody you aren't inputting any controls and the sticks are neutral you have to say something else is up. Well, one of our members is an electronics whiz with the phone company. He came out with some equipment and found the neighbor to our north had a souped wi-fi that was overpowering the 2.4 spectrum. It didn't matter is you had hopping technology or not, if you flew into the path of the wi-fi which covered half our flying field, you could lose a plane. Hitec, Futaba transmitters did it, too. Another person at the airport had an overpowered wi-fi aimed at right angles to the first one, so we were hit with a double whammy. We got on the horn to the FCC and talked with them about our problems and then went to our neighbors and told them what we found. In the end things were toned down and we haven't had the problems.
I'm not saying this is the cause of your problems, just a possibility.