Does it crash in Safe Mode (Hold Shift down while you click FF's icon to start it up)?
(Alt) Help > Troubleshooting information: on the right side, do you have a button for "Reset Firefox"?
If it's that old, it could be Profile corruption.
Possibly some errant 3rd Party .dll is loading with it and causing the crashes.
Have you updated any 3rd Party Plugins, such as Flash recently (you really should, you know,
if you really need them - but only from trusted sources, I always check Corrine's Blog:
http://securitygarden.blogspot.co.uk/ currently Flash updates, info, direct links, uninstaller, etc. is in the 2nd article down the page)?
You could also install Pale Moon to test whether it's something affecting Mozilla -based browsers or something more specific to your setup/Profile.
http://www.palemoon.org/
<McAfee Site Advisor = chocolate teapot. Last time I checked it, the free version was a minimum of 6 months outdated in terms of website 'checks' done, I doubt the pay version, if it still exists, is much better>