Since posting a comment on this: https://support.mozilla.org/en-US/questions/946538 back in March 2013 the question has been archived, but in my view was never resolved! The problem persists! I'm now running FF 22.0 under Fedora 17 on two different Dell machines. No evident crash reports, but FF can still lock during a visit to facebook with very unpredictable and non-repeatable results. Windows users have come to accept that an application crashing the operating system is part of normal software behaviour, but this does NOT happen to Fedora Linux apps. Today before posting this message, during a face book session I start to see some slow down so I run tcpdump (basic IP diagnostic tool) as root and low NOTHING.. the TCP/IP stack has crashed! Tried to kill tcpdump - NOTHING, tried to kill firefox - NOTHING, last resort attempt soft reboot - warning 'Firefox is still running shutdown anyway?" yes - operating system goes down, but not will not power off, have to hold power button until hardware power off. Issued about:crashes after a restart, but last crash has the same date as my previous post. Ha.. Conclusion I have a deep operating system crash as the result of a visit to facebook.... On the other hand, perhaps the NSA don't like me linking wikileaks.org and it's nothing to do with FF ;-)