Commented pdfs crash in Acrobat Pro 11.0.0

Running Acrobat Pro 11.0.0 on MacBook Pro 10.8.5 and iMac10.8.5 -- same issue occurring on both:

Clients are using the commenting tool and sending the pdf back to me, and I can open in In Acrobat Pro. But as soon as I touch their Comment icon to read it, the program crashes. I CAN open the doc in Reader and it works just fine. There is a long Problem Report generated,  which of course I don't understand, other than to notice one line that is in ALL CAPS, for what that's worth :

Any thoughts?

Thank you,
~carol