Firefox is unstable when many windows and tabs are open, even when using NoScript, Adblock, and Ghostery, as mentioned above.
Many crashes do not start the Crash Reporter.
See for yourself. Go to this URL:
(Mozilla does not allow links from Slashdot.)
Those are NOT ALL the crashes! Those are just the crashes that don't also crash the Crash Reporter.
The earlier version, 26.0 is crashy, also: