XP boot drive letter changed - won't finish booting

  • Thread starter Thread starter Brian Z
  • Start date Start date
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Brian Z

XP boot drive letter changed
Was "C"
Now "G"
- won't finish booting (looking for info on "C")

Any way to change this using Recovery console? Diskpart?
 
Brian Z said:
XP boot drive letter changed
Was "C"
Now "G"
- won't finish booting (looking for info on "C")

Any way to change this using Recovery console? Diskpart?
Click to expand...

Give this a try. Get a Win98 boot floppy (download one from
www.bootdisk.com if you need to). Boot your computer from the floppy.
Execute the command "fdisk /mbr". Remove the floppy and reboot into XP.
See if that fixes it.
 
Give this a try. Get a Win98 boot floppy (download one from
www.bootdisk.com if you need to). Boot your computer from the floppy.
Execute the command "fdisk /mbr". Remove the floppy and reboot into XP.
See if that fixes it.
Click to expand...

Dan,

that may be a recipe for desaster. It will not change the drive
letters anyway.

Hans-Georg
 
Hans-Georg Michna said:
that may be a recipe for desaster. It will not change the drive
letters anyway.
Click to expand...

Yes, it will. It achieves the same result the MS KB article mentioned on
your webpage does. The KB article forces XP to rebuild the partition
signatures by directly deleting the old signatures from the registry. The
"fdisk /mbr" trick forces XP to rebuild the partition signatures by deleting
the Disk ID in the MBR (which invalidates the old signatures). The XP
recovery console's "fixmbr" and Win98's "fdisk /mbr" are functionally
equivalent except "fixmbr" is smart enough to not touch the Disk ID. In
this case, we want the Disk ID deleted, which fdisk will do (albeit,
unintentionally). This trick was documented here about a year ago by Michal
Kawecki.
 
Yes, it will. It achieves the same result the MS KB article mentioned on
your webpage does. The KB article forces XP to rebuild the partition
signatures by directly deleting the old signatures from the registry. The
"fdisk /mbr" trick forces XP to rebuild the partition signatures by deleting
the Disk ID in the MBR (which invalidates the old signatures). The XP
recovery console's "fixmbr" and Win98's "fdisk /mbr" are functionally
equivalent except "fixmbr" is smart enough to not touch the Disk ID. In
this case, we want the Disk ID deleted, which fdisk will do (albeit,
unintentionally). This trick was documented here about a year ago by Michal
Kawecki.
Click to expand...

Dan,

sorry for my incorrect assertion and thanks a lot for the good
information! I didn't know this.

There is some remaining risk though, as sometimes fdisk /mbr
renders a disk entirely unbootable. I don't know what causes
this, but the warnings you see in many places are an indication.

Hans-Georg
 
Hans-Georg Michna said:
sorry for my incorrect assertion and thanks a lot for the good
information! I didn't know this.

There is some remaining risk though, as sometimes fdisk /mbr
renders a disk entirely unbootable. I don't know what causes
this, but the warnings you see in many places are an indication.
Click to expand...

Point acknowledged. The executable code portion of the MBR under Win98 is
not byte-for-byte identical to the WinXP MBR, and without decoding it I
can't prove the differences are benign. (I suppose if one were that
concerned, "fdisk /mbr" could be used to zero the Disk ID and then "fixmbr"
from the RC to exactly restore the executable code portion of the MBR.)
I've used the Kawecki trick a few times to fix errant drive letters, but I
know as well as you that just because it's worked a few times for me doesn't
prove anything. <g>

However, I think the hazard with "fdisk /mbr" probably concerns deleting the
Disk ID when you really don't want to. Yet, the MS KB method presents the
same hazard - both techniques regenerate the partition signatures, but that
may not always be a good idea. For example, if the OS partition was
originally something like drive "F:", then regenerating the signatures will
cause the partition to be reassigned as "C:", which I believe would render
the system unbootable. I think both techniques work only when we want the
OS partition reassigned as C:.
 
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