Hidden devices
From Attie's Wiki
When you unplug a device from your computer, Windows will remember it!
This can get annoying, cause device names to contain "#6" etc... To show hidden devices in device manager try the following in a command prompt (you'll need to have administrative privileges):
> set devmgr_show_nonpresent_devices=1 > start "" DEVMGMT.MSC
Then click 'View', and 'Show Hidden Devices'. Source: http://support.microsoft.com/kb/269155
