If you want to dig into it, you can post a bunch of that computer's crash reports (navigate to about:crashes) on bugzilla: https://bugzilla.mozilla.org/enter_bug.cgi?product=Firefox&c...

Or you can view several of them and see if there's a common pattern in the "Signature" field. Firefox really should only be regularly crashing if: (1) there's a real bug and the thing that triggers it, (2) you're running out of memory, or (3) you have hardware.

I don't know what the odds of faulty hardware are for a randomly chosen user, but they're much higher for a randomly chosen user who is seeing regular crashes.