JAB_Creations - 3:58 pm on Jan 12, 2012 (gmt 0)
graeme_p, Mozilla has stable, aurora, beta and nightly channels (to mirror Chrome's stable, beta and developer channels). When a new version comes out on your channel you're automatically upgraded unless you disable the auto-upgrade feature.
It's extremely undesirable as I keep separate profiles for each version of Firefox as I test older versions especially with people staying on older versions (I myself I am sticking with 8.0 until 10.0 enterprise comes out). Mozilla is on crack if they think I'm going to completely rebuild two profiles every 42 days for about an hour or two of my time, complete waste since there isn't anything worth upgrading for!