If you are using a 9ZH (if memory serves me correctly, my 10SXII was the same) then they automatically default to "low throttle" whenever the voltage drops to an unsafe low voltage. One gets everthing back after cycling the throttle stick back to the bottom. This can cause many to believe they are getting glitched or have a bad servo.
The fact that you have one good flight (and I am assuming you are using all digitals) I would suspect this could be what is happening.
1 - I would first check the switch as it may be intermitant (which would cause a similar symptom).
2 - I would cycle the battery pack and test in a vibration rich environment - e.g. tie it to the base of a dremel saw (this will provide the vibration), turn on the saw and test the battery.
3 - You may have one or more servos binding that is requiring high amperage peaks (this will temporarily lower the voltage) during/at particular servo settings.
4 - You may have a bad engine bearing or clutch bell support bearing. The glitching caused by something like this would cause the radio to intermitantly go into and out of failsafe. If you have your failsafe set to hold the last setting on all servos but to also move the throttle to idle, a bad bearing will generate enough interference to cause momentary lockouts that will cause the same symptom. Remove the backplate from the engine and check the rear bearing for any sign of rust or roughness)..... ditto for checking the vlutch bell support bearings.
5 - If you have not properly aligned the clutch to the bell, this can cause the start shaft to spin at the rpm of the engine and cause premature wear of the start shaft support bearings - this will also cause RF that can be similar to #4.
I hope this helps