[sylpheed:30971] "error occured while processing messages"

[Andrei Mircea]

Hello,
I just realized that I have a problem when trying to move messages from the input folder to another folder. I get an error window with the text reproduced in the subject of the present message.
In Windows this does not happen.
I tried both with the recent Sylpheed version 2.4.0beta3 and with an older one (2.2.9), the same error arises.
Where should I look for a solution ? thank you in advance.
	Andrei