Device Manager--Show Hidden Devices:
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1. Start | All Programs | Accessories | Command Prompt.
2. Type: set devmgr_show_nonpresent_devices=1
3. Type: start devmgmt.msc
4. Use the Device Manager while keeping the Command Window open.

5. When finished close the Command Window and Device Manager.
   Windows will now clear step 2.

To set this environment variable globally:
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1. Right-click My Computer.
2. Click Properties | Advanced tab | Environment Variables tab.
3. Set the variables in the System Variables box.

NOTE: Use this method only for troubleshooting or development purposes, 
or to prevent users from accidentally uninstalling a required device 
that is not connected to the computer (such as a USB device or docking 
station that is not connected to a laptop computer).