Hi again, I bring you some updates (still in troubles):
Updated BIOS to version BETA 0810... OK
Installed debian 6.0.5 netinstall + desktop env (for ease of use)...ok
For a shorthand install made:
apt-get install xen-linux-system
apt-get install xen-qemu-dm
apt-get install grub-efi-amd64
(last one just to try something new since it's an "UEFI bios" lol)...
Attach some logs from 3 "boot types".