I was trying to install SP1 today and got this error : Windows 7 and Windows Server 2008 R2 Service Pack 1 (SP1) installation error: 0x800F0A12 If you receive error "0x800F0A12" when trying to install Service Pack 1 (SP1) for Windows 7 or Windows Server 2008 R2, it means the installer can’t access the system partition of your computer’s hard disk to update files. Usually, this partition is accessible to Windows (although you can't browse it in Windows Explorer). However, in some situations, access to the system partition might be blocked after Windows has started. For example: The system partition isn’t automatically mounted, or made accessible to Windows, during startup. A hard disk containing the system partition was removed prior to beginning SP1 installation. Windows is running on a storage area network (SAN), and access to the system partition has been disabled. A disk management tool from another software manufacturer was used to copy (or clone) the disk or partition on which you’re trying to install SP1. My system is dual booted with Ubuntu Linux (10.10) on a completely separate physical hard drive. I also have a modded bios instead of a bootloader for Windows 7. I tried the mountvol /E command inside a dosbox (ran as admin) to no avail. I am wondering if perhaps the GRUB loader is interfering in some way but I do not know for sure. Is anybody else running a similar rig and/or having the same problem? I am downloading the SP1 update from MS and am fully validated already. Any suggestions or help at this point is greatly appreciated. Thanks ! TheDevilYouKnow.