vérifies que les touches qui activent le wifi ne sont pas à l'origine du probleme :
For how-to's and troubleshooting information on Wired and Wireless networking, browse to the Dell Networking and Wireless Support Center.
To turn the wireless antenna off or on, press and hold the Fn key, and then press the PrtScr key (repeating this will toggle the wireless antenna off and on).
For more information on how to turn the wireless antenna on and off on a Dell Computer, refer to Dell Knowledge Base article How to Turn the Wireless Antenna On and Off on a Dell Computer.