A user was trying to delete a folder in TFS just beneath the project node using the Source Control Explorer. They could not because the error message stated that an item in the project was locked by a user that has since left our employ. I tried to use the "tf undo" command, but it said there were no pending changes detected.
A closer observation revealed some interesting things. First, I turned on the option that allowed me to see folders that had been previously deleted. The error message mentioned above states that the locked file resides in a folder named "450SUM5". But, that folder had never existed in the project at any location.
The attached BMP file shows all of these issues clearly.