I am having an issue where I have a team of people sharing the same files and folders. The process that they use requires them to move PDFs from folder to folder, and they rename the files as they move them. They are getting the following message that seems to indicate that the file or folder are in use. They all sit in the same area. They reach out to each other to confirm that the file and folder are not in use. The error can only be eliminated by restarting the computer that is receiving the message. We had a similar issue in the past that was solved by Adobe support. Unfortunately the solution was not documented. I do know that it was an application setting.
Disable the Preview panel in Windows Explorer.