adaptec ACS-100 Enclosure for 3.5" HDD to USB - suddenly, no drive letter!

possible solutions :
-it takes the letter from an existing device, and cannot.
-try giving a fixed drive letter : http://www.uwe-sieber.de/usbdlm_e.html

nobus,

thanks but  usbdlm still does not make my drive letter visible.
I wrote to Uwe ...

In W2K:
Computer Management/Storage/Disk Management
shows  "Disk 2: Basic,  38.28GB, Online,  UNallocated"

how I can make above "Disk 2"  ALLOCATED in "Disk Management"  WITHOUT deleting
existing data and/or starting partitioning?

nobus,

thanks for the list, but why would I use data recovery ? I am not saying that my hdd is bad.
Or you think otherwise?

because you can loose the data by making it allocated.
you can try this :
USB no drive letter
delete the following key with regedit and reboot :
HKEY_LOCAL_MACHINE SYSTEM CurrentControlSet Enum USBSTOR

nobus,

I used GetDataBack and recovered directory tree and files. But what worries me is :

1) last Fri I put my hdd in the hdd-to-usb enclosure and connected to one Xp Home pc,
backed up data successfully, and then properly disconnected usb enclosure.

2) on Sun, when I repaired that XP Home Pc, i connected usb enclosure back, only to
my surprise that hdd in the usb enclosure is not 'visible' .  
I then tried to 'see' my hdd by connecting my sub enclosure to other PCs (W2K, XP pro) -
but to no avail.

3) only THEN is when I look into "Disk Management" and UN/allocated issue, BUT never ever
proceeded to the end of Disk Management's partitioning (with no formatting option) wizard.

4) So my hdd became 'invisible' BEFORE I even touch disk management and allocation issue.
It became 'invisible' between the steps 1. and 2. above!!!

Q1:
Why?  I just moved back and forth  hdd jumper to master and slave positions, that's all.
And of course, turned Adaptec usb enclosure's power on/off.

Q2:
Now, when I partition and format my hdd again, how to protect it from being 'invisible'
again when I use it in the Adaptec USB enclosure on various machines?

correction above:

...
2) on Sun, when I repaired that XP Home Pc, i connected usb enclosure back, only to
my surprise that hdd in the usb enclosure is not 'visible' .  
I then tried to 'see' my hdd by connecting my USB enclosure to other PCs (W2K, XP pro) -
but to no avail.
....

In most cases, it is due to installing drivers, or an upgrade.  --> try a system restore to a previous date
And you cannot "protect" it; just keep a backup of the data. The USB protocol is not nearly as stable as the IDE is.