Vista is not assigning driver letters to external drives, claiming "Unknown Device"

[Michael Faklis]

My Vista Ultimate laptop stopped assigning driver letters to new external
drives, whether external hard drives or thumb drives. Old thumb drives I
used in the past are still recognized. This problem is happening on my new
Western Digital 1 tb external drive, whether using USB 2 or Firewire 400.
It is also happening on my new SanDisk 8gb U3 thumb drive and a new PNY 1gb
U3 thumb drive.
When inserted, Vista starts loading driver drivers for the device, but then
claims the drive is an "Unknown Device". For the external hard drive, the
driver software installation finds the WD My Book USB Device, USB Human
Interface Device, USB Mass Storage Device, USB Composite Device, and then it
fails to find "Unidentified Device". Device Manger shows the WD My Book USB
Device under disk drives, and also an Unknown device under Other devices.
Disk Management shows the drive, but without a drive letter. My computer
shows nothing for this drive.
All of these drives work fine on my older XP Pro laptop.
Please tell me why a drive letter is not being assigned to this "Unknown
Device" and how do I correct this problem.

- Michael Faklis <[email protected]>

 

[Mark L. Ferguson]

Write caching may be set wrong, and you are failing to use the "Safely
Remove Hardware" option when needed. (Device Manager, drive properties,
"Policies" tab.)

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Mark L. Ferguson

..

 

[Bob]

Same problem here with WD external drive. I have not been able to find a
solution but I have found a pain in the ass workaround. I plug the drive
into my XP machine where it is recognized and then connect it back to the
Vista machine. Vista then recognizes it for a week or two then the cycle
starts again.

 

[Michael Faklis]

I ALWAYS use "Safely Remove Hardware".

I keep my harddrives set to "Optimize for Performance", and thumb drives set
to "Optimize for Quick Removal". However when attaching the new drives we
never get past the driver not found for "Unknown Device" and drive letters
are not set.

- Michael Faklis

 

[Michael Faklis]

I think my problem may be corruption in the registry, where drive letters
may be assigned.

The problem started last month. Prior to that I had no problems attaching
new storage devices. Then I bought a new PNY 8gb thumb drive certified for
Vista ReadyBoost. That memory stick didn't work in Vista so I returned it
and got the SanDisk 8gb thumb drive. That didn't work either. Now new
external hard drives and thumb drives aren't assigned drive letters, and
Vista claims they are an "Unknown Device". Hard drives and thumb drives
that were in use prior to the PNY drive still work in Vista.

- Michael Faklis

 

[Colin Barnhorst]

Do you have a system restore point far enough back that could get your
registry right again if that's the problem?

 

[John Barnes]

Ventured back into the pit again, Colin

Do you have a system restore point far enough back that could get your
registry right again if that's the problem?

 

[Colin Barnhorst]

Been here for about three months, John. But not in vista.general. No way.

 

[John Barnes]

I see. This is cross posted to general, too.

Been here for about three months, John. But not in vista.general. No
way.

 

[theresekirchner]

I am having similar issues with a new computer, now running Vista Home
Premium. My USB external drives are not installing properly and are coming
up "unknown device". They do not appear in disk management at all, and are
not recognized anywhere as mass storage devices. I have tried uninstalling
the USB drivers and reinstalling them, removing infcache.1, numerous
reboots... I no longer have an XP computer to access the information on
these drives. Help please? Anyone??

 

[theresekirchner]

To clarify what I am using/doing:
I have 2 hard drives, one from a laptop WD400 and one from a desktop. I am
using a USB IDE cable, which worked fine on my XP computer. I am trying to
do both hard drives seperately, and am running into the exact same issues
with both. Jumpers are off, both set for "master". Power supply used for
desktop IDE drive. Both drives power up and spin, but neither are recognized
by the computer as "mass storage device", and do not appear under disk
management. Both disks are from computers that crashed- the laptop mainboard
failed (confirmed by manufacturer) and the CPU failed in the desktop.

I am running Vista Home premium on an ACER Intelq6600 w/ 4GB ddr2 and 500GB
SATA.