There is an update
After uninstalled wicd and network manager (including the nm applet) I removed phisically everything that I found on the system regarding these items and I reboot.
Than I installed again Network manager and the nm applet (trhough wired LAN). Than I finally manage to have my wireless to work,and at MTU 1500. I rebooted many times, used the other distros of the multiboot, than tried again Sabayon and the wireless was still working.
Than I had the nice idea to try to get rid of the keyring (it annoys me), but I was unable to mange it from the Keyring manager simply because I could not find it (not under application, not anywhere else). So I uninstalled
When I reboot, I found myself without gdm, with the basic xdm (and of course no wireless). Following some posts I found I managed to have the wired lan to work (through eth0), so using equo from the terminal, I installed gdm and I reboot.
At least now I have gdm, but the toolbar is missing and now I do not know where to go and what to do [for toolbar I mean where you have the varies Gnome Menus, Applications, etc...].
Useless to say I should not play with what I do not know, but I am learning something.
Thanks a lot