I was not clear: the iwlist's scanning result comes from the working system.
On the non-working system, iwlist only lists the neighbor's access points.
Since iwlist has nothing to do with Network-Manager, Wicd would not do
better.
I took your advice of paying a closer look at the properties of the access
points listed on both system by iwlist. On the working one, there were three
access points on the channel 12, including the one I want to connect to. On
the non-working system, the scan did not return any of those access points. I
therefore decided to reconfigure the Wifi router so that it uses the channel
4 (used by nobody in the neighborhood). After its restart, it works!
It makes no sense to me that the same Wifi adapter would detect access points
on channel 12 when connected to a laptop but not when connected to another
one. If anybody could provide an explanation, I would help me stay Cartesian!
Happy gravmass and thank you!
