I tried placing it right after move_gravity() (I'm using a modified version of the the template function, though I'm not actually using movement.wdl at all). I also tried placing it directly after move() in the move_gravity section (thought it has to go after the my_dist section, otherwise the character's walking animation gets screwed up). I couldn't see anywhere else to put it...
But then, the problem exists in the Office level (though it takes a little trying to see it there), so the problem obviously exists in the template scripts too...
Actually, I've just done a quick check and discovered that the problem does indeed lie in the template script... If I just do a quick and rough move not using move_gravity, collision is fine. Guess I've got to dig deep into the template script to find the problem then.
Thanks Ronny, your suggestion helped me realise this...
Cheers,
Keith