three problems with nano

Hi all...I'm having 3 problems with a Nano. First problem is when running Blink program to test board pins, all pins seem to work correctly except the following pins: pin 8 remains on all the time. Doesn't blink, remains constantly on, even when outputting to a different pin number. Pins 6 and 7 don't seem to work at all.
Third problem is when trying to power the Nano with a 12v ATX computer power supply, it works fine for a bit, then the power led blinks and it shuts down. Seems to work at 5v and 9v no problem.
Any suggestions are appreciated!