Built in collision for a very complex object such as .x level is too slow for DBPro to handle: You would have to set the object collision to polygons - which is very slow for complex objects. Basically, the best suggestions I've seen involve the use of the Intersect Object function. Basically, you turn off the .x level's collision all together. Then you write your own collision function using Intersect Object. There are some very good examples in the snippets section. I suggest reading up on those.
"Droids don't rip your arms off when they lose." -H. Solo
REALITY II