I'm wondering if it could be a heat related problem. Since Michael reported very little sand or dust in his camera either computer chip malfunction or more like the expansion of materials causing excessive friction. I'm just a doctor not a camera technician so what do I know?
Another doctor here; we may not be camera technicians, but we're gods so we know everything
Seriously though: I was born and bred in South Africa and have been to Namibia. The climate can definitely be extreme but I've never heard of a lens falling apart like that. I'd be more inclined to think that there was some vital screw missing!