As an aside –  I have patched at least 4 personal machines to version 3.6.9 with no problem.

http://www.networkworld.com/news/2010/091410-mozilla-halts-firefox-security.html?hpg1=bn
Mozilla has stopped providing security updates to Firefox users as it investigates a bug that caused computers to crash last week.

Computerworld blogger Michael Horowitz first reported on the problem last Sunday after he tried to update older editions of Firefox on several different machines.

When Horowitz asked Firefox 3.5.11, 3.6.3 and 3.6.8 if there was an update, the browsers told him no newer editions were available. Firefox’s up-to-date versions are 3.5.12 and 3.6.9, which Mozilla released a week ago when it patched 15 vulnerabilities , 11 of them labeled “critical.”

….
Users who want to upgrade older versions of Firefox can download 3.5.12 or 3.6.9 from Mozilla’s Web site, then install them manually overtop existing copies.