[Users] Folder disappear

[x.lucio at laposte.net]

Hello
I use claws mail 3.8 on my ubuntu 12.04 box.
I've seen a strange behaviour these days (i cannot say it's brand new,
but i've just discovered this this week).
Some folder have disappeared from the folder view. They are still on the
disk, with all mails inside; but not displayed in the list. 
I've not made changes in settings or whatever.

Thanks in advance for help
Lucio