That happened to me last fall. I was doing a research paper on 3 separate topics, so I had a 4 windows open: my fun stuff window, and my 3 research windows. My fun stuff window probably had 3-9 tabs in it, but my research windows each had about 30 tabs of newspaper articles that I'd found on Lexis-Nexis.

Then Firefox crashed, and unfortunately for me, all of my Lexis-Nexis tabs redirected themselves to the main search page when they loaded. I was so upset, especially as the paper was due 2 days from then :P

Good luck!