I had problems installing win 7 sp1 on the dual boot system which has ubuntu installed. The error was 0x800f0a12, which meant nothing to me.
According to source from MS, this was “due to the automount policy for your machine being set to disable”. Whatever that is, the solution is simple:
1. Run DISKPART
2. automount enable
4. Install SP1
Works for me, and it’s all that matters.