EDIT: Nevermind, OP's car has been fixed. I'll leave this post here in case it helps someone else in the future.
Voltage related problems come to mind:
Voltage too low (alternator not charging, dud battery, bad connection, faulty wiring, bad earth)
Voltage too high (voltage controller fault)
The various controllers are quite fussy and can play up with weird faults if they don't get the right voltage. If you have a voltmeter check the voltage at the battery when you get one of the faults. With the engine running it should be 14 - 14.7V. If it goes under 12.5V that's too low, and 15+V is too high.
Even if the voltage at the battery is within range the fault could still be electrical, due to a poor connection somewhere or a faulty earth. But if it is intermittent it can be a devil to find