Thank you for the replies.

Okay so I go to the window and aim out doors, its mainly cloudy with a few breaks in it.

Set the camera to 400 iso, Auto mode, f1.8, got a shutter reading of 1/250th, cock the shutter and fire, all is fine.

Now I change the aperture to f5.6, light isnt consistent but now it gives me 1/60th, cock and fire, locks up, three minutes later still hasn't released. This time I have undo the battery cover to reset it?

Set to manual, f5.6 @ 1/60th, all is fine.

Back to Auto, same settings, first time fires but sounds slow, second time sticks.

I have read about cleaning the shutter magnets on an OM10 and guess this may be similar but what confuses me is why it works fine in manual, surely if the magnets were dirty it would stick/play up what ever.