Everytime I swithc from ACHI to IDE in the BIOS, Windows 7 does not load up. It will say that there's an error with starting windows and it suggests to do a Windows Recovery or Start Up Normally. If I switch it back to ACHI it loads up fine. I read up online and found that changing some things using Regedit will work but It will not for me.
Just to be clear, the mode that the hard drives are accessed is specified in BIOS: Either IDE or AHCI. Whatever is specified is how Windows will see the drives, and Windows will load the appropriate drivers when it is first installed. If you change the access mode in BIOS after Windows is installed, then Windows will boot with the wrong disk drivers and usually blue screen.