i'm having issues trying to install any OS( tried Ubuntu 9.04/ windows 7/xp) onto my hard drive whenever i switch to ahci mode in bios. i get the message ntldr is missing, please restart computer. i can't seem to find a setting in bios that would let me install an operating system. (message appears before i see installation options). tried to change the boot order, doesn't work. if i try to install in IDE mode, everyting is working perfectly. Anyone has any clues. The Gigabyte Motherboard is the GA-MA785GM-US2H. (785 NB, SB710). the hard drive is Seagate 750gb 7200.11. and the dvd rom is the samsung s223.