Windows 7: Missing Operating System Windows 7

kansasjhawk · 29 Aug 2010

I am getting the "Missing Operating System" message on boot. Here is the strange thing...if I change the boot order in the BIOS and have CDROM first and choose not to boot off of it Windows 7 loads fine. If I put HARDDISK first then I get the missing operating system message. I have tried running CHKDSK, BOOTREC and the plain old Windows repair util. None of them have worked.

Anyone have any ideas?

Dwarf · 29 Aug 2010

Hi kansasjhawk and welcome to Windows 7 Forums

That's a strange one.

Normally, if you have a bootable OS disk in the drive, and the drive is higher up in the boot order set in the BIOS than the HDD, then a message will appear asking if you want to boot from the drive, and to press any key if you do, failing which booting will continue with the next device in the boot order. The actual order doesn't matter normally, unless you specifically need to boot from floppy or CD/DVD.

Just out of interest, what interface do your HDD and optical drive use (PATA/IDE or SATA)?

gregrocker · 29 Aug 2010

Boot the Windows 7 DVD Repair console or Repair CD, make sure Windows 7 partition is marked Active: Partition - Mark as Active

Now boot back into DVD Repair console or Repair CD, click through to Startup Repair to run up to 3 separate times to repair or rewrite the MBR to Windows 7 partition: Startup Repair - Run 3 Separate Times

kansasjhawk · 29 Aug 2010

Fixed it. I just had to restore the BIOS defaults...even though all I had changed was the boot order. As long as it is fixed.....

Bare Foot Kid · 29 Aug 2010

Thanks for the update, your info may help someone else.

Windows 7: Missing Operating System Windows 7

Missing Operating System Windows 7 problems?