This has happened to me twice in the last year! For no reason and without warning, Thunderbird came up with all of my email accounts missing, and running the email set-up wizard. When I went into the folder where the email files were stored, it was as if I had just installed the program (settings, etc. were gone). I'm developing the habit of copying the Thunderbird folder to another location so I don't lose everything again. I love the flexibility of Thunderbird (haven't used outlook/express in years.) Has any else run into this issue?