There are a dozen questions already about Microsoft Office files being locked from editing, but not this exact question. So I hope it won't get marked as a duplicate.
I went into Computer Management this morning and connected to a server so I could close an Open File that was open by "Smith, Bob", a colleague. All good. But then an hour later when I went to open that excel file again, the same user had it locked from editing again ("Smith, Bob"). A user who is on vacation this week. His domain user cannot be accessed from outside the company building. It's not him. And sure enough, it was open again on the Share by his user.
What can cause a file to be reopened by a user who is not in the building? This file isn't accessed by any processes or databases or anything.