Potzato: I may be completely out of the subject, but did you try every possible USB port on your laptop ?
I wonder if it's possible you damaged your "concentrateur USB", it happened to me in the past : I partially lost two juxtaposed USB port that way on my old laptop :( (if I remember I could still use mouse, but not devices with high transfer rates)
Irrelevant detail : It's my desktop, which has this issue. My laptop connects to the wifi just fine.
But to answer your question : yes, I've tried in all usb ports. AND i have tested these ports with an usb flash key, that I seem to be able to open, so I guess the usb ports are fine...
Now, if usb ports can be "half damaged", I'm not sure with what to test them...