I am experiencing the same issue, too. I tried to uninstall and install the software again but I didn't have luck. I wish there's someone who can help us.
Exactly the same here, on a 2010, 27" iMac, 3.2GHz, with only 4GB RAM. It is running OS 10.11.4.
So far I tried the cleaner tool, re-installed ID, deleted the users account (I'm the team Admin), re-instated, and re-installed.
No change. The rest of the CC suite we use (Illustrator, Photoshop, Bridge, Acrobat DC) all function perfectly.
I'm sure this won't be the answer for you, but I merely restarted my machine when I had this problem this morning. Because it worked for me, though, I'm posting it for the record.
Good luck, people.