Windows: folder or file open in another program

When you try to move a folder:

    "The action can't be completed because the folder or a file in it is open in another program"

This stunningly unhelpful error message has persisted through many versions of Windows.

The way I work around it is:

• Rename an unrelated file or folder nearby, then rename it back again.
• The original folder or file should now be "unlocked"

You can always reboot to fix it, too.