if the following applies to your version of Ubuntu / Nautilus:
https://bugs.launchpad.net/ubuntu/+s...s/+bug/1043614

Problem: calling up properties on a DNG / PEF / NEF / CR2 (and possibly others) in nautilus makes nautilus hang. The only way is to kill it.

Reporting as a new bug is also fine and marking as duplicate is also fine, I assume.

It's quite embarrassing that basic functionality of an OS has bugs.

Thanks