1. Go into c:\documents and settings
2. Click on tools\folder options\view - click on show hidden files, and folders.
3. Click on your profile\application data\thunderbird\profiles
4. Copy the folder to a blank cd/dvd/ext hard drive.
5. Reload computer - Thunderbird, but do not move contents of folder back to c:\documents and settings\profile\application data\thunderbird\profiles until you have created a new account.
6. Complete steps 1 - 3 again. This time look at what the folder is named, and rename the folder that you have saved to the new folder. (If it's on a CD\DVD your going to have to copy it to the hard drive before renaming it).
7. Copy/move the folder back to c:\documents and settings\profile\application data\thunderbird\profiles
8. Open Thunderbird - All email/folders should be there.
9. Export/save your Address Book before reformating your computer.