A search for this problem brought me to https://support.mozilla.org/en-US/questions/1002714 but the solutions offered in that thread do not work. An upgrade from XP (outlook express) to Win 8.1. On old machine imported Outlook Express successfully into TB, then moved profile to new Win 8.1 machine, where this problem occurs. Redirected the .ini file, however discovered that a) many folders, although showing, contain no email, and b) some folders do not show subfolders. Check using explorer directly into the profile shows that all email are in their correct place. The one consistent factor is that it's the folders that have any Japanese text in their names (TB is English version) are the ones which do not show email (nor display any subfolders if they have them); i.e. the folders display correct Japanese names, but are empty. Any folder that is written wholly in English displays email fine (also subfolders and contents display fine). Email written in Japanese display fine in these English-named folders, so it seems to be just the folder names which cause this problem. Moving the folders with Japanese characters in them from 'Outlook Express Import' folder to subfolders of Inbox on TB on XP PC, then transfering profile over again has no effect. I don't know if this is a Win 8.1 issue but it seems more of a bug in TB? First attempt at a solution is to rename the Japanese folders into English and see if that works. That will be tedious so if anyone has any other ideas, please advise. Many thanks.