The Adobe Acrobat Reader plugin is currently causing problems for most Mac OS X users who have it installed. In the majority of cases, the plugin shows a blank page when a user clicks on a link to a PDF file. There are also reports of crashes when using the plugin in 32 bit mode. For this reason we have decided to add the plugin to the blocklist.
Mac OS X users who have this plugin installed will be prompted to disable it in the next 24 hours. You will have the option to keep it enabled, and even if you disable it when prompted, you will have the option to re-enable it in the Add-ons Manager. We are not blocking the Adobe Flash plugin, only the Adobe Acrobat NPAPI plugin.
We are currently working with Adobe so that a fixed version is released soon. We will post an update on this blog once that happens.