I'm currently in the second part of the Mantellan Crux (the bit with the pyramid) and I can't get the bottom trap door in the pyramid to open (the one near the seducer).
I've clicked every grave stone but can only get the top trap to door to open (and close).
It sounds as if something is happening when I click one of the other stones but nothing actually happens.
I've tried running fixsave on my save game, I've tried exiting and reloading before clicking the stones.
I've also tried reloading to before the crux and going through to this point again.
I'm running Daggerfall using DosBox 0.74 under Windows Vista.

Any one have any thoughts on how to get around this and on to the next part of the crux?

If I can't get unstuck I'll have to place Daggerfall in my "done" pile without actually completing it and that would be a pity.

That one is operated by the southeasternmost gravestone. Make sure you aren't accidentally clicking them twice (it'll open and close again)

I have a save game at the top of the pyramid.
If I load this save and descend inside the trap door is shut.
If I load this save, go down to the graves, click the correct one (hear the click & groan), then descend inside the trap door is still shut.

Is there any way I can tell if I'm only clicking the grave once?

I just had another thought about this: does the trap door actually look open (like the one above)? Or do you have to stand on it and it'll give way?
I haven't ever actually stood on it, because it looks closed.