Solution
Restart Windows Explorer using the following steps:
via
Autodesk - AutoCAD Civil 3D Services & Support - Windows 7 Explorer fails to restart after uninstalling an Autodesk product

Click here to view the entire blog post.
Restart Windows Explorer using the following steps:
- Start the Windows Task Manager
- Choose File -> "New Task (Run...)"
- Enter explorer.exe in the edit field
- Click OK
via
Autodesk - AutoCAD Civil 3D Services & Support - Windows 7 Explorer fails to restart after uninstalling an Autodesk product
Click here to view the entire blog post.