So it looks like removing the extensions has indeed paid off. You may recall my earlier post noting my concerns about the reliability of Firefox 3 and questions about the cause. After uninstalling the few extensions I had installed in the Firefox 3 release candidate and using the default browser install for four days now, I've not seen any crashes:
So that's good, obviously. However, not to belabor the point, but to the end user, a Firefox crash is a Firefox crash. In the same way that one might blame, say, Windows Vista when there's an incompatible device driver, one might likewise blame Mozilla when the browser crashes, regardless of the actual fault. I'm not saying this is fair, just that it will happen.
I should also mention that Mozilla has been quite attentive to the issue and has asked for a lot of feedback. Their activity and interest is commendable.