Several step process:
1.) Add a System Environment Variable, named
DevMgr_Show_NonPresent_Devices
set it's value = 1
*System Properties, Advanced, Environment Variables
System category
2.) Device Manager, Click View - tic/check "Show Hidden
Devices
3.) In the following categories, locate all entries shown in
diminished tone or grayed out and Right Click, choose
uninstall ( Unplug all USB Flash/Drives prior to starting ).
a.) Storage Volumes
b.) Universal Serial Bus Controllers
1.) All "USB Mass Storage Controllers"
c.) Disk Drives

Re-plug each Flash/Drive, once enumerated, use DiskMgmt.Msc
to set it's Drive Letter assignment to a mid-alphabet letter, such as
L or M.

"RalphieUK" <RalphieUK@discussions.microsoft.com> wrote in message
news:6FB97621-DCB8-4EB5-84FB-32E3C346D666@microsoft.com...
>I have the same problem and it's driving me crazy as I can't access my
>flash
> drives or usb card reader. Thanks
>
> "Ron Carr" wrote:
>
>> When I plug in a USB external disk drive, or a flash memory card, the
>> device
>> does not show in Windows Explorer. Disk management shows the disk drive
>> (not
>> the flash memory) but it has no drive letter and I cannot assign one
>> (Change
>> drive or path grayed out). I do have an E: drive which is evidently the
>> memory card port on my photo printer - never used. (I have 2 hard disks C
>> and
>> D, my CD and DVD are assigned P and Q).
>> Thanks for any help.....I threw away a flash memory card figuring it was
>> no
>> good!
>> Ron