I think I know why it crashes. A fellow guy in a site told me that the brush faces are concave, and that is not allowed in Valve Hammer Editor. The .obj file is imported from a N64 .rom, and the brushes are usually concave. The only way to fix it is to make them convex. I don't know how to do that, but atleast I know the cause. :(
https://developer.valvesoftware.com/wiki/Concave
https://developer.valvesoftware.com/wiki/Concave