I've noticed this problem for a long time. I have many scripts installed, most of them are from
userscripts.org and providing update URLs. If I right click any of them and then choose "check update" it would be updated (if it does have) without problem. But, they never get AUTO updated, for months. I've set extensions.greasemonkey.requireSecureUpdates to false so it won't be the problem.
Today I'm going to figure this problem out so I just started a new profile of Firefox, installed GM (also set requireSecureUpdates to false), and then installed an old version of a script. (my choice is
http://userscripts.org/scripts/version/118033/563189.user.js ) After only about 1min, Firefox told me it has been auto updated to newest version 3.2.0, which never happens on my main profile.
How can I fix this problem? I get tired to manually update my scripts once and once again..