HOw to Turn off the library for device number cannot be determined?

Product: Windows Operating System
ID: 128
Source: Removable Storage Service
Version: 5.2
Symbolic Name: LM_NO_DEVICE_NUMBER
Message: The device number of a(n) %1 cannot be determined. This device failed to configure. This event may be logged several times for the same device.

Explanation
The Removable Storage service could not configure a media library because it could not get device-related information.

User Action
Turn off the library, wait a few seconds, and then turn it back on. The Removable Storage service should automatically reconfigure the library.

how to turn off the library?
regedit?
services?
help me..thanx