I cannot pin folders to my Windows Explorer Icon on the Taskbar
I recently had this problem on my Windows 7 x64 machine. I was able to ping other applications and URLs but folders.
I found the solution on one of Windows forums, I thought that it might also help you so I am sharing here.
It was due to corrupted jump list files stored in a hidden folder on %APPDATA%\Microsoft\Windows\Recent\AutomaticDestinations.
You can see few files there, I didn’t know which one is corrupted so I moved them all to a subfolder that I named as “Corrupted” and tried to pin a folder and it worked.
I hope this helps you too.