Sorry, but I can't. It is one of those rare bugs that affect only some people. I cannot reproduce the bugs, so I cannot fix them
There is one, possible, cure. But it forces you to begin anew. Make a teleporter from Hall of Champions right to the lowest level and back. Some people have reported that you will not experience crashes in levels above the maximum depth you have been.
I have done this trick in my newest dungeon (Return of Chaos) and so far I don't think I have seen anyone report any crashes...
I will prehaps make a new version of Grave, which includes a similar teleporter thing, when (if?) I get enough time. I will need iron a couple more bugs out too... (one door that shouldn't be is open and one set of stairs lead you back to the original dungeon... Possibly there were a couple other more minor bugs too.)
I really wanted to get into this dungeon because from the jump start I already noticed some very clever and innovative object and door placements. I managed to get to the Firestaff level but I just can't make it down a set of stairs enough times without it locking up. I even moved some stairs around and managed to get downstairs to a couple of other locations and thought I got a way Scott-free but alas, another crash. Oh well, Toni, if you get a chance, perhaps you could iron out all the stair related bugs and upload a new version? It was really a very cool dungeon while it lasted 
