MountedDevices key: Misbehaving drive letters

MountedDevices key: Misbehaving drive letters

Post by Howard Kai » Tue, 24 Apr 2007 21:55:06

I've got a multiboot system with Win 2000 SP4 on each.

REcently, I decided to add Linux, so I repartitioned two USB drives as

USB-1: Logical drive O (NTFS), followed by a Linux ext3
USB-2: Logical drive P (NTFS), followed by a Linux Swap partition.

On all but 1 of the OS, the drive letters are as desired, but on one:

1. Looking at My Computer, S is also assigned to the P drive.
2. Looking at Disk Management, only the S is shown.

Is it safe to take the HKLM\System\MountedDevices key from one of the
properly behaving OS, and import into the misbehaving OS?

Or do those keys get automatically reconfigured each time I reboot?

If not, how do I fix this?

The difference between the misbehaving OS and the others is the misbehaving
OS was installed OVER Win 98, whilst the others were clean installs.

MountedDevices key: Misbehaving drive letters

Post by Howard Kai » Wed, 25 Apr 2007 15:13:20

That was my tought too.

Yes, it's the same problem.

But both misbehaving and correct OS have the same versions of mountmgr.sys.
system32\dllcache and system32\drivers have version 7006, the hotfix was
version 6897.
$NTUpdateRollup has the hotfix version 6897
the SertvicePack i386 directory has version 6661.

I guess that I'll try the Workaround suggested in te article, but not change
mountmgr.sys as it seems to be more recent than the hotfix.

Is Mountvol.exe just an info utility?

I'll do a full system backup with Acronis TRue Image, so I can restore the


MountedDevices key: Misbehaving drive letters

Post by Mark » Thu, 26 Apr 2007 05:20:19

[ ]

Seems reasonable and is "MS supported".

Mountvol serves a different purpose, but it's default display might
reveal 2 drive letters for the same "disk device" and be useful, or
not, in this case. Note that 'volumes' on a physical drive device
_will_ dislay the same ID strings.

[ ]

Please post a follow up as I am not sure if any of this will be a
permanent fix. Hope so.

MountedDevices key: Misbehaving drive letters

Post by Howard Kai » Thu, 26 Apr 2007 19:46:58

The first thing I'll do is compare the HKLM\System\Disk key between two OS.
Since they are on the same PC, they betta be the same.

Then I'll compare the Mounted Devices key.
The signatures should be the same for corresponding drives on all OS.
If so, then removing the extra keys in MountedDevices may be all that is

If this works, the remaining question will be whether the settings stick for
each reboot.

MountedDevices key: Misbehaving drive letters

Post by Howard Kai » Fri, 27 Apr 2007 19:14:34

I just compared the HKLM\System\Disk and HKLM\System\Mounted Devices key for
tge misbehaning OS (call this C), and the properly behaving OS (call) this

The Disk key on C is 996 bytes larger than the Disk key on J.
Is there a spec for the Disk key so I might compare the detailed contents?

The MountedDevices key on C is 20KB, whilst Mounted\Devices key on J is
I suspect that MountedDevices on J is larger due to *** left behind by
Acronis TRue Image9 and Ghost 10 when mountind a volume from a backup

Is there a spec for the MountedDevices key so I might compare the detailed

In a few minutes, I'll use TRue Image to get the latest backup so I can
restore images.
After that:

1. I'll try editing the MountedDevices key on C as suggested in KB article
2. Then I'll boot to C a few times to see whether the settings stick.
3. If the settings do not stick, I'll try to delete the Disk and
MountedDevices keys on C, then immediately reboot.
Result might be interesting.
4, If all fails, I'll restore the C drive frof the backup.

MountedDevices key: Misbehaving drive letters

Post by Howard Kai » Fri, 27 Apr 2007 21:39:37

Progress is my least important product.

1. I compared the HKLM\System\Disk keys for all 3 properly behaving OS. For
some reason, the Disk key differs in the Mishaving OS.

2. I then applied the workaround frm KB article 836662. Situation worse
thgan first thought.
Not only was S duplicating P, in the MountedDevices key there was a missing
N and a non-used T.
I deleted the entries for S and T, rebooted and everything looked OK, But my
glee was shortlived, I booted again and this time th eduplicate S
re-appearded and N and O were missing in the Mounted DEvices key, tho
present in My Computer.

3. So, what the heck, I imported the Disk key from one of the other OS.
Rebooted. THis time, as I recall, the MountedDEvices key did not have the
duplicate S, but N and O were missing in the MountedDEvices key, yet My
Computer displays the duplicate S, as well as the missing N and O.

So, this issue is a lot deeper than as described in the KB article.

The problem appears to occur only in the Win 2000 that was installed ove
rWin 98.

Guess I just gotta live with it.

MountedDevices key: Misbehaving drive letters

Post by Mark » Sat, 28 Apr 2007 01:40:57

[ ]

Can that be 'corrected' by way of a 'clean' install?

Thanks for following up. Wish I could be of more help. Have you
already tried (maybe) the MS "hardware" groups?

MountedDevices key: Misbehaving drive letters

Post by Howard Kai » Sat, 28 Apr 2007 01:55:37

Not enough disk space on the C drive.

Actually, with few exceptions, I use the OS on the C drive only when I need
to compile something using Office 97, or Office 97 itself.

Probably not worth the effort of re-installing.
If I did, I would remove that OS from boot.ini, remove the Windows
directory, and they try a clean install on C. Then re-install the apps.

This is a software issue as the other OS on the same PC have no problem.


MountedDevices key: Misbehaving drive letters

Post by Howard Kai » Mon, 30 Apr 2007 07:41:21

First, the GOOD news.

The problem is not caused by having installed Win 2000 over Win 98.
How do I know?
The BAD news is that the problem occurred on another one of the OS.
I use the fix in the KB article mentioned elsewhere in this thread.
I hope that the settings stick.

However, as the KB article points out, there are timing issues.
I guess these are exacerbated by having Linux partitions as well as NTFS
partitions. Also, today, I converted one NTFS to FAT32 so the partition's
files coild be shared 'tween win 2000 and linux.

Note that in at least one OS that has correct drive letters in My Computer,
the MountedDEvices key omits one of the drives.

I expect that this problem will recurr.