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Messed up MBR!

Last response: in Windows XP
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December 21, 2010 11:46:03 PM

OK I have been a bad boy, I admit it!

Now I hope I can enlist your help to get me out of trouble and back up and running. :) 

I'll make a long story short.

My system:
WinXP SP2
Four drives: c,d,e,f
At the moment the built-in USB ports don't function at all (busted).
I have just installed a PCI USB card with 4+1 USB ports, but can't boot with the 4 so far.
No floppy and my CD/DVD drive is a USB drive.
So basically I don't have any fall-backs to boot with.

In my haste, when I installed Syslinux on f:, I wiped out the MBR!

Now when my system boots, it boots to f: (PING) and I don't know how to fix the mbr so I can get back to WinXP on c:.

If anyone can get me out of this jam I would REALLY appreciate it!

More about : messed mbr

December 22, 2010 3:44:38 PM

Get a cd drive that you can connect otherwise your out of luck, you need some way to boot your system to be able to run the win cd to repair your mbr.
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December 23, 2010 1:49:23 PM

What motherboard are you using? Some mobos, like mine, can be configured in the BIOS to boot off USB devices. I have booted from USB sticks and a USB floppy drive. So there may be an easy answer to your question.

For extra points, what BIOS and what version is on the mobo (watch the boot messages). Do you know how to interrupt the boot process into BIOS?

Once you can boot on the DVD, you can do an XP system repair.

=======================================

More fun solution:

Install a third-party boot manager. Any good one will allow you to boot to the partition boot record of any of your partitions, so that you can install, restore, and mix-and-match OS installations to your heart's content.

After you install one, you will be able to just add your Windows partition to its list of boots.

Backup your disk first, just in case.
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Edit: If C, D, E, and F are actually separate hard drives, not partitions on the same one, than your installation on F did not mess up your MBR on C. You can go into the BIOS and change the boot drive priority back to the C drive. What might have happened here:

- The only drive on the system with an installed OS and active partition is C, which is the third drive.
- You install an os on F, which is actually the first drive, attached to SATA port 1. This installs an MBR on F:, and marks the partition active.
- The machine boots. The first drive it sees with an active partition is the F drive, so it boots off that.

This is why I put my boot drive on the first SATA port
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December 23, 2010 7:19:04 PM

Quote:
What motherboard are you using? Some mobos, like mine, can be configured in the BIOS to boot off USB devices. I have booted from USB sticks and a USB floppy drive. So there may be an easy answer to your question.

For extra points, what BIOS and what version is on the mobo (watch the boot messages). Do you know how to interrupt the boot process into BIOS?

Once you can boot on the DVD, you can do an XP system repair.


Thanks for helping out!
I'm using an AOpen i855GMEm-LFS mb.
As I mentioned all of my mb USB ports are busted!
My USB PCI card won't allow me to boot off the ports, therefore no
booting to an external device.

Quote:

Install a third-party boot manager. Any good one will allow you to boot to the partition boot record of any of your partitions, so that you can install, restore, and mix-and-match OS installations to your heart's content.


Can you recommend a good one? One that will allow an XP boot by default and runs quickly on bootup?

Quote:
Edit: If C, D, E, and F are actually separate hard drives, not partitions on the same one, than your installation on F did not mess up your MBR on C. You can go into the BIOS and change the boot drive priority back to the C drive. What might have happened here...


I have only one hard drive. c,d,e,f are partitions on the same drive.

TIA
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December 24, 2010 6:43:16 PM

Accolite is right - if you can't boot off a floppy device connected to the PCI card, then you have a tougher problem. You need to either
a) Borrow an IDE (mobo controller) or SATA (Promise RAID chip) DVD drive to boot from, or
b) Install a boot manager while running Syslinux.

The latter case is probably better, since you could install it through your running OS, then configure it to boot both of your OSes. However, we've gotten beyond where I can help you. I don't know of any boot managers that can be installed through a running Linux OS. Not that there aren't any, but it's outside of my area of knowledge.

Any decent boot manager will run quickly and let you make XP the default. Maybe someone else will weigh in with one that you can install thru Linux.
Remember to do a full disk backup that can be restored to a runnable state before trying this, or you may end up with an expensive coaster.
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!