I'm working on a massive project based on the AO engine, basicly it's a medieval game, set in a dutch town... more info soon

Anyways, we're trying to get the most out of the old engine, as you will see on the following screenies. Almost all scenery is made out of full 3d models which made me ran into a couple of serious issues.
The models all look fine, there's no clipping on the models themselves and AO does a great job at loading em into the engine, however, there's a problem with models completely disappearing (while remain loaded) from view. My guess is it has something to do the players line of sight or to many 'lines' getting in front of a model. The strange part is however, that some models remain perfectly loaded and other models disappear in front of them. Sounds impossible, but once you see my map file you'll get the idea

It's hard to explain this issue, also because I'm pretty sure hardly anyone has ever done a lot with 3d + AO apart from Jemmet.
But if someone has a clue about what is going on, that would be much apriciated.
On this screen the tip on top of the tower (3d model) is perfectly alright http://img266.imageshack.us/img266/7278/tower1xn3.jpg
2 Steps backwards and it disappears completely from sight but not from the map: http://img259.imageshack.us/img259/1036/tower2ol1.jpg
Here's the map file in Forge with all the models: http://img99.imageshack.us/img99/5663/forge1ts8.jpg
Here's the map file in Forge completely nuked: http://img266.imageshack.us/img266/6783/forge2aa1.jpg
Every bit of help would be great. Thanks, -Tim