How large ur map? Usually its 'small triangle pieces in one place' issue, but... Acording google... you overload engine possibilities and bsp-tree engine just cant handle so complicated geomethry as you trying implement. I saw some reminders about 'patches' to engine, but i dont think its solution.
Once some time ago i had weird error. Small enough map, compiling is ok, but ingame i have a lot artifacts in my map. Just 'caus many 'details' i trying make with simple struct/detail brushes.
Try think about simplifying of ur map. =)
