And what operating system might that be?
OS X 10.11.3
Unfortunately, El Capitan (Mac OS X 10.11.x) doesn't work well with CS6. There have been numerous reports of problem in this forum. CS6 is almost four years old. It was never tested for compatibility with El Capitan, and will never be updated.
Your best bet it to roll back to a previous Mac OS X version, or get a Creative Cloud subscription to InDesign CC 2015 which is supported
Thanks for the info. Kind of guessed that may the case. Will have to subscribe sooner than planned.
Photoshop also been a touch unstable, Illustrator seems Ok though.