Having uninstalled Boot Magic, I understand that I need to run FDISK /MBR to restore the master boot record to its previous state. I have a couple of questions about this:
A recent thread implied that this was completely safe. Is this really so? No pitfalls at all?
FDISK is not part of WinXP, which I’m using. It is part of Win98, which I don’t have. Would booting to DOS and using the DOS version of FDISK be okay?
You’re not hoping to preserve the contents of your hard drive, are you?
I’ve never had any problems at all with ‘fdisk /mbr’. It seems pretty safe an reliable to me. YMMV 
There are always pitfalls and freak occurrences, strange configurations, etc.
IIRC, I used the DOS fdisk on drives with NTFS partitions back with NT4 with great success.
mangetout, fdisk /mbr doesn’t affect the contents of the drive, unless you have a certain configuration (such as something like hard-disk encryption that needs to load a driver from the bootstrap, etc.). It only replaces the boot loader with a generic boot loader. That being said, it can probably also screw up a dual boot system.
I would suggest booting from the Windows XP CD and going to the Recovery Console. There’s a command available from there called fixmbr that might be better to use, since you’re using only XP. See also the link at the bottom of that page for fixboot.
Not that fdisk will necessarily not work, but I’ve just never tried it, and it makes more sense to me to use XP’s version if that’s the OS you’re running.
I didn’t know that (I’ve only ever done /mbr with wiped disks and I assumed it was destroying the FAT too) Thanks for the info.
Hauky, thanks for pointing that out. Never used it before, but it looks much better than fdisk.
That was another one of the big risks of fdisk /mbr, if the partition table had been screwed up as well as the mbr, you’d hose the disk for sure (some boot sector viruses for example would alter the partition table too, IIRC).
Thanks for the useful guidance.
I will try Hauky’s Recovery Console suggestion. It sounds as if this could be a good technique for dealing with various problems.
IIRC, fdisk for Win9x machines doesn’t work for XP.
Take a look at http://support.microsoft.com/support/kb/articles/Q255/8/67.ASP
Did someone say FDISK?
I have used fdisk.exe for a number of years… and I know that the win98 version works great if you are adding a new hard drive to your system, even if using Win2000 or XP.
As far as the /mbr switch, i never used it before.
FDISK replaces the boot sector with another copy of the boot sector that is stored on the hard drive. If that other copy is corrupted, your computer will no longer boot. You’ll need to break out your XP CD and use the repair option. As was previously mentioned, you may want to use the XP tools anyway.
FDISK cannot handle NTFS formatted drives. WinXP can use both FAT32 and NTFS partitions, so make sure you know which one you have before you start mucking with things.
Windows 95 and DOS both cannot handle FAT32 partitions (they only do FAT16). You need a windows 98 boot disk if you are going to do this.
I’m wondering how you did that. If you have a primary NTFS partition, FDISK can delete it or at least tell you about it (it will call it a non-dos partition, IIRC). But if you have an extended NTFS partition, FDISK gets really confused. It will tell you that there are logical drives defined, but then when you go to view them (or delete them) it will tell you that there aren’t any.
As for the FDISK /MBR option on an NTFS partition, I have no idea what would happen, but I suspect it’s not good.
It can’t read the partition and simply doesn’t boot at all. It doesn’t show the “Starting Windows 95” type message either. You can then repair the boot sector from the setup if you want.
I did this recently because I didn’t think that the machine would have an ntfs partition. I ended up using knoppix to remove it because dos fdisk wouldn’t.
AHEM.
The various fdisk options almost amount to different operations. I have used fdisk /mbr safely on drives containing data, but other parameter switches, or invoking the main program without parameters and making changes with it can cause a major recovery disaster.
The advice given thus far has been good, but a lot of posters casually left out the /mbr parameter (understandably). Verba sat…
Here’s a follow-up:
Per Hauky’s suggestion, I booted from a WinXP CD and ran the Recovery Console (RC). Invoking this is reasonably self-explanatory. You do need the Administrator password. You do not need the exact WinXP disk from which your operating system was installed.
Once you have invoked the RC, you can type ‘HELP’ for a list of available commands, and ‘HELP [cmd name]’ for details about any one. I ran FIXMBR, and despite some dire warnings it did exactly what I wanted. Other commands look interesting, though I did not conduct an extensive investigation.