Laura, that is exactly what happened, and not the first time. Definitely the worst "lock-up" though. I think the main benefit of firefox is the way this site responds to it, compared to the other ones I've worked with on this computer. Thankfully, it really doesn't occur that often. Previously it has cost me ...um...maybe ten minutes, tops. This one was a monster. I had to re-start my computer.
Well. As I said, I've tried other browsers and I think this one works the best for this site. Two steps forward...
Hopefully not three steps back again!