Fix Missing Operating System Error
If you're having boot problem on your Windows PC related to the following error: "Missing operating system", then you can easily get rid of it, using Emergency Boot Kit, and boot your PC like before.
This article explains how to fix Missing Operating System error, related to Windows 7 and other operating systems, by setting active partition flag in the partition table.
1. Symptoms of the problem
When computer is powered up, an error message "Missing operating system" appears (white-on-black letters in text mode and blinking cursor):
2. Normal boot sequence
Normally computer boots as shown below (Windows 7 boot sequence is shown as example):
3. Defect in the boot sequence which leads to Missing Operating System error
Defect in the boot sequence which is a reason for Missing Operating System error is shown below:
4. How to fix Missing Operating System error
1) Download Emergency Boot Kit and deploy it to USB thumbdrive according to the instructions, then set up your BIOS to boot from USB thumbdrive. You need full version of Emergency Boot Kit to actually write changes to the disk, but it's recommended to try demo version to make sure there are no hardware incompatibilities.
2) Boot from Emergency Boot Kit, wait until the main menu appears.
3) Find boot loader for your primary OS in the list. Please note that "called by BIOS" radiobutton is off:
4) Click on the radio button "called by BIOS" for bootloader of your primary OS. It should be turned on now:
5) Click OK to close the window and then choose "Reboot" in the main menu. Missing Operating System problem is fixed now.
Please note: Mount & Boot Center verifies entire boot path from BIOS to the OS boot loader, so other boot problems may be automatically fixed at this point.