In Windows Explorer, the Navigation Pane is the pane displayed on the left with the tree of all drives and other directories. If your computer is on a Windows domain (say at work), it might display a lot of network computers under the title Network.
If you do not want this list of Network computer displayed, the remedy is easy. Head over to Network and Sharing Center. Choose Change Advanced Sharing Settings and click Turn off Network Discovery.
Tried with: Windows 7