Pentax ME Super overexposing

I just took over my family (hardly-used) Pentax ME Super. I've been out on two shoots and my images are generally over-exposed by a few stops (which means they are unuseable dammit). I was shooting in Auto mode. The light meter seems to be working OK, and the camera seems in great nick. I have put new batteries in each time. Any ideas?

is the whole roll OX or just some shots?
Did you set the film speed correctly?
Can you cross ref the meter with a handheld or other cam?

Jayson