A while ago I bought a Toshiba netbook which of course came with Windows 7 startup. Since I was going to be putting 4 OS’es on it (Windows, Ubuntu, Chromium and Meego), I was switching from the usual method of booting directly into Windows, into using Grub2. Of course now that the SP1 update has come out, it doesn’t install properly. This is the support page that the error pointed me to: http://windows.microsoft.com/en-US/windows7/windows-7-windows-server-2008-r2-service-pack-1-sp1-installation-error-0x800F0A12
Unfortunately, none of these options worked. It turns out, it is a simple fix (at least for me). In start menu, type “disk management” into the search, and click on “create and format hard disk partitions”. Right click on the partition that has Windows7 (likely the largest NTFS partition [don’t select the recovery partition] if you have a setup like mine) and click “Mark Partition as Active”. Then try to install SP1 again, and it should work fine.