My computer (well, Windows XP) failed. I got everything off the HD, including my Firefox profile, which I especially wanted because I had lots of open unsaved tabs in my current session (yes, I know that's bad practice!), but also to rescue bookmarks etc.
I've now got Windows 7, and reinstalled Firefox. I've read the instructions on the Firefox website about creating new profiles, and I'm not sure they're very intuitive. It says that you can copy all the contents from an old profile into a new 'default' one, which I have done (http://support.mozilla.org/en-US/kb/back-and-restore-information-Firefox-profiles). However, when I open Firefox, the data from this profile isn't being used and Firefox doesn't seem to recognise the data that's there. What am I doing wrong?!