Thank you all very much. This is very useful. At least i know a procedure that is supposed to work.

Anyway, I have an update of 1 minute ago. We switched on the laptop for the 100th time, without any configuration change from the last 7 or 8 reboots, during which I could only connect by entering the WEP manually; and, this time, it did connected automatically. This is completely puzzling to me.

The only difference I am thinking of is that the laptop was, this time, powered using the power cord. Do you guys think it is possible that while on battery the wireless interface was somehow powered down, maybe just during boot? Some wrong energy saving settings?

Also, maybe this time, for some reason, some configuration file was properly updated, deleted/recreated?

The laptop is being used by its owner, in this very moment, but we'll have few more Macs to work on in the next days. Hopefully not this one, but I don't know what to expect at this point.

Thank you a million for your step-by step procedure. By looking at it I seem to have done all that you listed, but I am not sure aboutnr. 10.