You're trying to rename a folder in Windows and Windows tells you "The action can't be completed because the folder or a file in it is open in another program."
What, Windows? Really? OK, I'll close all the programs I'm running. But that didn't help. What could be wrong?
The solution that worked for us was to tell Windows to stop creating hidden thumbnail files and then yelling at us when they are in use.
Step 1: Go to Folder Options
In Windows Explorer, click the Option key to make the hidden menu appear, then select Tools / Folder Options.
Step 2: Tell Windows Not to Use Thumbnails
After doing this, we were successfully able to rename folders.