Had a problem with several MSWord files that I was unable to rename, delete and when opened from Explorer were always indicated as in use by MSWord. Checked permissions on the files and folders, checked Read-Only flag and it was cleared. The file was not open in MSWord and I was trying to change the file name, or delete, in Explorer.

I started Task Manager and found a copy of Winword running. I terminated the task and was able to rename the file. I then clicked on the file again, tried to rename, system said the file was open in Winword. Started Task Manager again and sure enough Winword was again running even though I had not started MSWord. Hmm, what was going on.

I could find no reason why Winword was starting. Then I resized the explorer box to full size. On the right was the preview screen. This preview was what was starting Winword (MSWord) and because Winword had the file open for the preview the file could not be changed or deleted.

I turned off the preview in Windows Explorer and all is well.