I found just clicking on the room I wanted to get to after pulling the lever was the perfect way to know if anything had happenned.
On the subject of the end of the game, I've just completed the game for the second time. This time I completed all of the quests before banging the gong.
My problem is I let out a load of scorpions (about 20 of them), as soon as I got close to the Lord of Lies or whatever he's called. They slaughtered him (and his mate) in pretty quick time. But then the game froze, the cut scene or end movie did not play and he and I are left there looking stupid.
I'm not too bothered because I'd finished the game before, but I wondered why it happenned.