Hi Mark - you're probably using Rhino v4 and MoI v1?

MoI v1 was not able to read the unit setting out of a Rhino v4 file properly.

You have a couple of different options - if you save from Rhino as a Rhino version 3 3DM file, then I think that should work.

Another option is to use MoI version 2, which is currently in beta release available from here: http://moi3d.com/beta.htm - MoI v2 should be able to read the settings properly from a Rhino v4 file.

Probably using MoI v2 is easiest since you don't have to do anything to the files for that case.

Please let me know if none of those options works for you.

- Michael