I attached the source file I used to render .bsp files. It's a heavily modified version of the one from gametutorials.com. I modified it to use Direct3D9 and use triangle lists instead of fans. Maybe I should have included the entire project source. If you need it, I'll upload that too.
So far, my BSP loader is the only one I've ever seen render the Simpsons Q3 map correctly (besides Q3 itself), which is the most complex Q3 map I've seen to date. Hopefully this helps.
PS: Be warned, it's messy!