@Fabio: Which version of Ubuntu are you using? Feisty?
I previously thought the problem had gone away since Feisty (in Feisty's current state, anyway), but I've recently had problems, again, in connecting to unencrypted networks... It may have been another, more general problem, though, as I wasn't able to try to connect to an encrypted network at the time that it was acting up.
@Fabio: Which version of Ubuntu are you using? Feisty?
I previously thought the problem had gone away since Feisty (in Feisty's current state, anyway), but I've recently had problems, again, in connecting to unencrypted networks... It may have been another, more general problem, though, as I wasn't able to try to connect to an encrypted network at the time that it was acting up.