My computer has 3 disks:

  • 1 SATA SSD 256GB, one partition: Windows 7 (C:)
  • 1 SATA SSD 256GB, one partition: Data (F:)
  • 1 SATA HDD 750GB, three partitions: Data (E:, G:, L:)

The mechanical disk (HDD 750GB) is faulty and I can merely list its directories. But if I remove it Windows doesn't start anymore and BIOS/UEFI asks for a valid boot media.

Using the disk manager of Windows 7 I discovered that it has a 100 MB partition at the beginning, without any letter assigned, with this description: "system, active, primary partition).

Instead, the C: drive has: "boot, paging file, primary partition". I also add Windows now take about 15-20 minutes to boot and to shutdown, I bet due to the required access to the faulty disk.

I've already recovered important files on the HDD, but I'm not sure what I have to do to keep Windows booting even disconnecting it.


This is one of those Windows bugs that has been around since forever. Essentially, your boot loader installed to your data drive during Windows installation because it was in a lower numbered SATA port. If you don't mind wiping out your Windows installation, your best bet is to unplug your data drives and reinstall with just the OS disk connected. If you'd rather not just reinstall, you'll need to shrink your partitions on your OS drive and make room for the boot partition at the front of the drive using a linux bootable disc and gparted or similar. After that, you'll still need to unplug your data drives and use your Windows install media to rebuild your boot loader.

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