>Recently I have been getting deadlocks in my application.
>What causes a deadlock ?
>Can it be avoided ?
>How can it be resolved ?
>What causes the "File is in use by another user" to be generated ?
>I understand how a record can be in use by another user but why the file ???

You can find the list of commands that lock entire table and other info about locking at http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fox7help/html/dgtsklockingdata.asp.