I have been forced, by repeated interruptions to my work telling me that software had been downloaded, to upgrade Adobe Reader through two steps, first to 9.3.1 then to 9.3.2. This is a pure pain because I do not use Reader, having switched to Preview precisely because I was fed up with the constant "upgrades". In this case I was forced to use Reader by a customized document I was sent to review. The "upgrades", first to 9.3.1 then to 9.3.2, continually interrupted my work until I gave in a tried to install them. 9.3.2 crashed my Macbook twice refusing even to allow a soft restart or shutdown. Finally I was forced to navigate through the Adobe website to find and install the "upgrade". It cost me more than an hour, lost concentration to say nothing of the anger and frustration. Why are you wasting users time and sending out stuff that does not work (just look for this forum to see how much unnecessary grief this is causing people). Just STOP doing this: ONLY send small upgrades when security issues make it unavoidable. Otherwise offer upgrades and give good reasons why users should choose them. I don't care whether you publish this on your forum; I just want you to know that this kind of behavior convinces users to abandon your products as I did. WHY do you do it?
Since you don't use Adobe Reader, the easiest way to stop the updates is to uninstall it.