After a few attempts, I have come to here : http://leo4all.wikidot.com/know-issues

My system reboots right after EFI is initialized

Some computers are just not able to run Leopard properly, this is mainly due to incompatibilities between the BIOS and Leopards ACPI platform. You can try a different BIOS revision, maybe you find one that works. Some people have success booting with cpus=1 bootflag at Darwin.

I have tried it and now i'm installing Leopard!

Regards