Ok, I did some test in another scene, and I assembled a group of objects together and added a Target helper and then a camera. Collisions work great...   created another grouped object and dragged that into the first group... still works good.

Something is odd, did a test by draging in the viper. no prob... collisions worked, then I grabbed the existing groups into the viper. WORKS...

Now here is what happens if you save the group as a car file and then create a new scene with a terrain (zeroed so its flat)

I import the car group collection.. and BOOM I get the freeze when I try to use collisions.

Now the reason I saved my car setup with the UFO's was to get everything set up in a smaller room and then import it into a larger scene to make it easier to construct my set without dealing with vast distances.

Is there a way to import prepared .car files without having this problem or is this a bug?

Carrara 7 Pro, Anime Studio Pro 8, Hexagon 2.5, Zbrush 4.6, trueSpace 7.6, and Corel Draw X3. Manga Studio 4EX, Open Canvas 5, WACOM Cintiq 12WX User