I will try to make the long story short : system : Dell xps 1645 HDD: Seagate ST9500420ASG SATA PGP full disk encryption - including the boot sector I installed Windows 7 Manager Utility - I accidentally disabled AHCI feature from windows. => permanent BSOD STOP 0x0000007B I tried to set the hdd in Bios from AHCI to ATA, but I got the same BSOD I tried to boot in safe mode - same BSOD I think the problem may be solved by reversing the settings in HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\IastorV back to original value for AHCI - 1 I tried to boot using system recovery - > system recovery does not recognize an operating system because it does not have the SATA drivers. I looked on Seagate page for the drivers, on Dell page - and everywhere I could for the drivers - no luck. Can anyone tell me where to download the Standard SATA drivers ( sys - inf) ? I tried to follow this : Error message when you start a Windows 7 or Windows Vista-based computer after you change the SATA mode of the boot drive: "STOP 0x0000007B INACCESSABLE_BOOT_DEVICE". I can not use the utility in start-up mode because of the HDD encryption. I can not modify manually the registry in system recovery because I do not have access to the HDD due to incorrect AHCI settings. Due to the fact that I am using full disk encryption, I can not use a recovery utility such as active@disk or Windows 7 DVD because the information is unreadable. I have extremely valuable information on the HDD - I can no afford to lose it. I think that a link to a proper SATA driver would solve the problem. Thanks for reading and I hope you can help me.