Blottooo

Wondering if anyone can tell me what it means when the power light on the dash flashes. After my car gets to running temp or just above, the gearbox behavious becomes erratic. It changes gears sporadically, in and out of overdrive, back and forth through second and third then when i turn the car off, the power light on the dash flashs 16 times. Any help or explaination appreciated. Cheers, Pete