Nick White , Sep 13, 2007; 06:40 a.m.
'there is now no film in it' - are you absolutely sure of that?
It really sounds like the film has been exposed (ie at the end of the film) but has not been rewound. To rewind the film there is a small recessed button on the underside (under the grip if I recall correctly), pressing that releases the winding mechanism enabling the film to then be wound back into the cassette.
If you are 100% sure there is no film in the camera, then opening the back may reset it. If you open the back when there is an un-rewound film in it, the film will be ruined - so maybe best to open in the dark (eg in a cupboard) just in case.