Problem send text with letter "w"

Hello, 
I think I have a problem with this library.
I perfectly manage to receive messages into arduino with this librairy (and with AT command) but when i send messages from arduino via ethernet shield and webservice it's work with all the letters except "w" which deletes the rest of the message. exemple: i send "hello world" i receive "hello w"

Do you have an idea ?
Cordialy,
Antoine.
