Acrobat crashing: fill in form fields

acrobat is crashing when i try to use the "fill in form fields" or "add your signature or initials" buttons.  neither of them fly out when trying to use/open them, they both cause the pdf to crash.  the drawing and other tools seem to be working fine.  

It's happened on two different pdf's, the same type i've had no problems with in the past.  I've rebooted, and uninstalled  / rebooted but all with the same results.

thanks!