Let's start over. Locate the profile on old computer. Look for the appdata>roaming>thunderbird>profiles.ini file. it is likely in appdata>roaming>thunderbird>profiles with a name of seemingly random characters. Copy that folder and store on old computer with a meaningful name, such as TBIRDPROFILE. Now, copy the file to new computer and store it anywhere you would like (I put mine in the c: root, e.g. c:\\TBIRDPROFILE. Now, right-click on the desktop shortcut for TB and add -p preceded by a space or two to the target line to the right of ...thunderbird.exe" and close the shortcut . Now, start TB and it will show a menu to select your profile. Select 'create profile' and browse to and select the one you just placed there. TB should now work with new profile. Once you confirm that all is okay, you can remove the -p.