Could it possibly be a scaling issue ?
I had a similar issue with collisions but my scaling was way off on those objects with problems.
I've also heard similar issues with faces being inside out using blender for the models.
A simple workaround is to create your own invisible collision objects and just place these at the
location of your objects you want collisions. That worked well for my night driving game and
didn't have a bad effect on the frame rates, but really depends on how many objects you have.
Apologies for repeat post I see that you have been on the blender tutorial page, just thought I
could help someone who has not only helped me so much in the past but has been a valuable
help and support person across the forums
fubar
