What the server OS is. For example on Windows Server 2008, here's how to see who has a lock on a file -> look under Computer Management (on the server) to see who the files are in use by (under Shared Folders/Open Files.)
Bob
There is a file on our network that is in use often and sometimes people forget that they have it open. How can I view who is using the file? How can I boot the person using the file?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic