I'm having much the same problem as jaydee, but I AM using the magic carpet script (If that actually does anything).
The Dts plus exporter works fine, without collision. As soon as I add a collision box it screws everything up in game. And I can't export with the old dts, because I want my model flatshaded.
All my LOD's are set to 50, if thats any use.
Edit: Kinda a big bump, but I thought it was needed as the question wasn't really answered.