Firefox closes / quits at random

[Young]

Firefox will suddenly disappear while I'm reading. I don't have to be 
doing anything at the moment for it to happen.

My usage style might be different from most.
Every time this has happened I've been using an aggregater (Google News, 
Reddit, Digg) and clicking the center wheel to open numerous tabs for 
later reading. It's when I'm reading one of those tabs that it happens.

I've never seen anything like this before from Firefox.

This started about 5 days ago, and after awhile I blamed an add on for a 
zooming feature which I was using a lot. I removed the add on, and was 
okay for about a day. Now it's doing it again.

Anyway else seeing this?

Mark