as cgsheen said "Your motherboard has a nvidia nforce chipset. There's a problem with Zephyroth 10.5.1 and nforce SATA controllers... "

i guess that's the problem with me. i do have a nforce motherboard + sata hdd.

cgsheen's solution is to "insert the proper .kexts into a new Install .iso"

i've got no idea how to do this, so i'm just waiting...

btw, formating the partition for MacOS in FAT32 did't work for me.