The question is, what else have you done to your system that might be affecting FF? Have you updated any libraries recently, for example? Installed new extensions? Deleted or removed something? Are there any specific patterns to the crashes?
Second, have you tried Firefox with a new profile? That's usually the first thing to try when you have problems. Or try reinstalling the whole program.
Really though, for Firefox, you'll probably get better help over at the Mozillazine
forums. They're the ones with the in-depth knowledge. They've always been able to help me out.