Nick,
Have you read the tutorial: Using Rhino surfaces

This tutorial covers:

> Inserting provided Rhino files

> Sketching on the appropriate planes/faces

> Using the Trim Model function

....

> 1. In a new part workspace, from the Insert menu select Surfaces...


As far as I know, there is no *.3dm direct import option.
( I use Alibre Expert 64 bit)

Looks like you have installed a third-party plug-in, which caused the problem.

( Maybe it was a similar problem to -> http://forum.alibre.com/viewtopic.php?f=1&t=12687)