Still happening. URLS that get pushed way down in the list have a little box that says they're open on my other computer - which has been turned off for hours or days in some cases!

You can bookmark the sites and give them a two-letter keyword so they are guaranteed to autofill.

Thanks, but how do I make Mozilla fix the actual problem? It's been doing it again

The order of bookmark and history items on the drop-down is based on "frecency" -- a formula which considers frequency and recency of use. Over time, the score can change if you visit the site less or more frequently. I don't think there is a way to lock in the order.