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I have been running Windows 8 on a different partition, alongside Ubuntu 12.04, working fine.

After running sudo apt-get upgrade the Windows 8 partition can't boot. I can still see Windows 8 (on dev/sda3, which is correct) in the grub menu, but when selected I see a black screen flash and the grub menu reappears within a couple of seconds.

I tried repairing with boot-repair which has always solved my grub issues, but this time it changes nothing.

FWIW here is a BootSummary

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Do you have a Windows repair disk? Perhaps BOOTMGR (the Windows Vista/Seven/Eight bootloader) has become damaged.

If you have a repair disk, I would try using the automatic repair utility to fix the bootloader.

If you don't have a repair disk, I would try booting from Hiren's Boot CD, running BootICE, and overwriting your Windows drives' PBR (partiton boot record) with BOOTMG. You can do this by selecting your hard drive from the dropdown list, and clicking Process PBR on the bottom of the Window. Unfortunately, I you can download Hiren's Boot CD from HERE.

Please note, you may have to disable UEFI to boot Hiren's. Also, If you have SATA, you may have to enter you BIOS/UEFI settings, and set your SATA controller to emulate an IDE controller. Otherwise, you might not be able to access your hard drives from the CD at all. After you are finished with he CD be sure to set your BIOS/UEFI settings back to whate they were before, or else Windows/Ubuntu might get confused by the changes, and fail to boot.

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If you are still trying to use the system as a dual boot system, you can go to and download that program and you will be able to edit you master boot record.

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Solved by following

Basically, use the testdisk program from a Live (USB/CD) environment to fix the Windows partition boot sector.

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