Sign up ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

This has happened twice now. I wake in the morning (yes noon is morning) I go to my computer to find it is stuck in the middle of rebooting. The last few lines of the log show the following.

GRUB loading stage 1.5.
GRUB loading, please wait...
Error 21

Isn't GRUB a bootloader for Linux? I've messed around with Ubuntu on this computer, but my last OS install was a clean format and install of XP. I've never actually seen this come up when I personally reset the computer, only a couple of times when it's reset on its own late at night.

I'm worried that I have some virus that is trying to reboot my computer into an instance of Linux that I didn't install. Has anyone seen something like this before? How can I fix it?

share|improve this question

2 Answers 2

up vote 3 down vote accepted

The MBR probably wasn't fixed correctly. A typical fixmbr doesn't always fix things properly, but MbrFix is what I'd recommend. Simply use this command:

C:\path\to\mbrfix.exe /drive 0 fixmbr /yes

replace C:\path\to with the path to the mbrfix program.

share|improve this answer
now that sounds pretty scary, John: "However, users can accidentally delete partitions and important data." – Molly7244 Dec 13 '09 at 21:26
If you specify the wrong drive. A windows CD isn't needed for this method either. – John T Dec 13 '09 at 21:29

How can I fix it?

boot from your Windows XP CD into the Recovery Condole and use the following command:

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.