I had FF set for auto updates, but it hadn't done them for a while for some reason. Anyway, the update didn't work, and even worse, simply closing FF without using CC kills off my last session even though I have the right setting in OPTIONS selected...
...this is weird.
Never happened before and I've been using FF and CC for years. I'm not very geeky when it comes to comps so can't think of what else could fix it. I like to use the restore session feature a lot; saves on having to make lots of unecessary bookmarks and time opening and selecting the right bookmarks.