MS Word add-in problem

With Acrobat XI professional (not with standard verson), when creating a pdf from the open Word file, it often crashes Word program (I am using MS Office 365).

The Acrabt add-in in Word disappears and has to checked to show up on Word tool bar. Everytime!

Is it problem with MS Office 365 or Acrobat or confined to its professional version itself?

Please help me from insanity.