I've searched on this topic and have never found an answer. We are running Adobe Professional 8.1.2 with all of the latest released patches.
The complaint - At random times users complain that the URL is gone from the preferences page.
-These users only have one site that they go to so it is not a matter of deleting and forgetting to make the entry.
-They make numerous comments to many documents and with no change in their process the URL is missing. The first clue that they know it is missing is when a document is opened the Comments Toolbar is missing the last two icons to Save Comments and to Send the Comments. They re-enter the URL and the icons reappear.
-Any clues or resolutions to making this entry static? This was an occasional issue in V7.0.8 and is a regular issue in 8.1.2.
http://www.acrobatusers.com/collaboration.pdf
use
http://192.239.92.41/collaboration.pdf
Lori Kassuba is an AUC Expert and Community Manager for AcrobatUsers.com.