Problematic Firefox add-on, how to make it work?

Hello there,
Recently I upgraded my system to latest version and it went pretty well and good without any problem. The problem triggered when I try to save an Adobe PDF document from the website. For your information, I have Adobe Reader too in the system and that too updated. I do not understand why I got this error message. Is anything terrible wrong? Please help. Thanks.

Add-ons may be causing problems
Firefox has determined that the following add-ons are known to cause stability or security problems.
Adobe acrobat NPAPI Plug-in, Version 10.1.3 10.1.3
