Well, as I said, if I don't modify the setup, but just select "Erase entire harddrive" to let it set up partitions automatically and then "Finish partitioning", Everything works!! It installs GRUB, which can then boot Linux! (I'm posting from such a setup.) The automatic setup is: 20G /, first primary, ext3, boot=ON 384M swap, second primary This _works_. With the same BIOS. So the bug is not in the BIOS.