Hi Gaieus,
Thanks for the reply. I've attached the file below, please do let me know what you think. Perhaps the contours messed up the model?

model which cant be opened on PC

Hi all, please could someone solve my problem.

I have drawn my sketchup model on my mac Powerbook (SU 6.0.1145) and now I want to import it to a PC (to render in Maxwell). The SU on the PC is the most up to date version. I thought it will open fine, as they are both SketchUp Pro. However, the "unexpected file format" message comes up...

Surely I don't have to dwg or other formats and then import it into the sketchup on the pc?