[Wolfgang]

Well, when my team first tested out our drive train, we had many random communication loss too, only it happened more predictably. This happened either when we tried to move one of our joysticks back or when the bot managed to move a certain distance away from the driver station. I beleive our problem, and solution were actually quite simple. We just had to tighten some loose wires. I do not know if this is the cause of your problem, but I think it's worth a shot investigating.