Yes, same error, and with the supergrub it boots just fine.
AHCI is definately ON because otherwise my Windows won't boot.
About removing the ATA option... how do I do that? I just tried boot-repair and enabled ATA support, which helps nothing. Maybe you mean I should try without enabling the ATA option? However, these are grub options, right? So if somehow the system is unable to load grub, will these options make any difference then?
PS: new boot-info report: http://paste.ubuntu.com/5611444/
EDIT: Boot-repair has an option to repair or reinstall the MBR, so I tried that. Instead of "read error" I then got "operating system not found". Then boot-repair again to reinstall grub (without ATA checkbox), and now I have the "read error" again.
Maybe I could try to downgrade my bios version to see if that helps?