From what I've read some speed controls (blue ones in particular) they tend to have a weak BEC, 1amp. When you have a hot modified, a digital servo, and a personal transponder all plugged into the spektrum receiver it can experience a voltage loss. This can also happen to 1/12 racers since we run 4.8v with 19t motors.
To help prevent this go to either stormer hobbies, or horizons web sight and pick up some spektrum voltage protection devices. All it really is, is a 4700uf capacitor with a receiver lead soldered on, there like $4 or something.