Keyboard disappears during install with dual athlon mp

[Gianluca Cecchi]

I have a dual athlon mp that I'm trying to reuse for educational
purposes as an ltp server.
I tried f7, ubuntu 7.04, edubuntu 7.10 and mandriva 2007 inst cds/dvds
but all stops after few screens in the sense that keyboard doesn't
work anymore.
In f7 it stops in the screen where i have to select language that is
already a text one and so no way. Same for *buntu.
In mandriva the install is graphical from the begin and i notice that
the system is not frozen because with the mouse i can select different
buttons, but I'm stopped anyway because I have to provide keyboard
input to then proceed...
Keyboard is ps/2.. I've not usb keyboard but I'm going to try...
Any other suggestions? Could it be anything kernel related and
eventually bypassed by any boot switch option?
Gianluca