CC 2015 is a bugfest. Downgrade to CC 2014.
As Mylenium says, reinstall CC 2014 to continue working. There's a big bug-fix update coming at the end of this month that should fix a lot of the big problems with CC 2015.
Thanks. I wish I would have thought of that before wasting two days watching the spinning beach ball. It's previewing again! Woo hoo!!!
Thanks Mylenium and Szalam.
I really hope the update that's coming in a few weeks fixes the majority of bugs people are experiencing. I want them to enjoy working in CC 2015 as much as I do.