I noticed that all the folders I have created in Thunderbird, using a symbol at the beginning (for sorting purposes), like a period (.) or an exclamation mark (!), gets the folder corrupted and the following symptoms will be noticed: A) the corresponding file name of the folder will be a random generated characters like eege90ge67 B) the contents of the folder will disappear (deleted perhaps?) C) when you create a sub folder in that folder, it duplicates itself D) when you create a sub folder in that folder, it cannot be deleted E) in case you delete the initial folder or subfolders, they cannot be removed from the Trash folder, either they give a message, freeze the system or just re-appear after a restart. I have plenty of space on the SSD HD, have a fast machine, been using TB for more than 5 years and just recently I started to rename the folders with symbols. Any feedback or solution would be appreciated.