All messages mentioned in replies #195 to #207 have been fixed automagically thanks the last forum software update.
According to Mr Scottie, empty messages were due to the fact that the forum database and the forum software were communication in ISO-something. That's why some characters like é or à were not recognized and led to blank messages.
Since the last software upgrade, the database and the software communicate in UTF-8, this way all characters are correctly read, messages are not lost.
Thus the database and the software communicate better, they are far happier and me too since I don't have to fix empty messages anymore! :D