UPDATED ON: January 15, 2017
USB Drive Letter Manager (USBDLM) is a Windows service that gives control over Windows' drive letter assignment for USB drives.
When a removable drive (USB flash drive, flash card reader, portable hard drive) is attached for the first time, Windows mounts it to the first available ' local' drive letter. If there is a network share on this letter, Windows XP will use it anyway for the new USB drive because since XP network shares are specific to the current user and not visible in the context of the system where the letter is assigned. The USB drive then appears to be invisible. This is fixed by SP3 in most situations.
You can change the letter assignments in the Windows Disk Management Console with a lot of mouse clicks but you have to do it again for every new device.
And, for USB devices that have no serial number (in violation of the USB standards) you have to do it too when you attach it to a different USB port.
All functions are applied to USB drives at the moment they are being attached, when the USBDLM service starts up and when a user logs on.
USBDLM runs as Win32 service under Windows 2000, XP, Server 2003, Vista, Windows 7/8 and Server 2008 (R2). An x64 version for the x64 Edition of Windows is available too.
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