FIREFOX - WINDOWS vs. TABS???

I searched around, but could not find an answer.

I like to have a LOT of windows open when I am researching and working on the internet. Previously, when I opened FF, it would save all of my windows in the exact order that I had them in during the previous session, but recently (last week) the first row was last and the last first and jumbled in between. Why? Is there a way that I can manually put the windows in the order that I want them in? I don't like Tabs, but I'm willing to use them if it will prevent the windows/tabs from getting out of order (chronology is important in the work I'm doing). TIA, any help is GREATLY appreciated.

 

Did this happn after a FF updating?? I've heard a few odd things have been happening. I lost my Start Page and didn't get it back until
I uninstalled FF 9.0.1 and installed FF 10.3 Beta!!!!

 

No, I "think" I haven't allowed FF to update because the last time I did, I lost a LOT of my History!!! :< Thanks!