I have been using Lightroom since Lightroom 4 and had never had any problems.
Since the recent upgrade (I have CC) Lightroom CC I imported a few times no problem. But a few days ago I can not import any new photos, not from the camera, not from the Mac HD, not from a separate Hard drive.
The program simply crashes.
I have clean up the preferences, but I am at a loss at what else to try.
Thanks to this post (Re: Lightroom freezes on import if a video file is present in the folder/card) I have found out the problem in import is due to the presence of video files. Without them Lightroom CC 2015 works just fine.