Imported mesh terrain landscape and rigidbody skier causing updateMassFromShape error

I have the above error. I have a mountain landscape mesh (terrain) imported from sketchuppro. I have a mesh collider component added to the mountain landscape. I then have imported a skier with 9 mesh parts (I added it to a prefab under a parent folder called "OrangeSkier". I've applied a rigidbody to the OrangeSkier. Each of the 9 mesh parts have mesh colliders attached to them also. I get the updateMassFromShape error mentioned above, and when I hit Play, the skier just bounces around upside down and all over the place, rather than sliding down the mountain like I want. I realize that one of the 9 mesh shapes maybe a plane surface, or one with a hole in it, but I can't figure out how to find or fix that.

I've attached 3 screenshots showing settings at the link below. I'd love some help, and will reciprocate on this forum whenever possible. :)

Remove the mesh colliders from the skier; mesh colliders are for static background objects without rigidbodies. Use a primitive collider (or compound primitive collider) for the skier.