Locked files

I have a shared folder on a Windows 2003 storage server that our developers use. Recently there are many cases where files are being locked and users cant delete them. Checking the locks by Unlocker I can see the the system process is the lock holder.

It looks like the system will keep the lock on even if the user does not access the file anymore. Is there a way to set the system to release these locks? is there a parameter that tells the system how long the lock will be kept after the file is closed?

More information

The user that runs the application that gets locked is on a terminal server. when the application runs, I can see via the Computer Management/Open files that the file is being opened and the name of the user is displayed. Once he exists the application, the file is kept open in the list, but now the username is changed to the terminal server computer account name. The file is still locked.

Thanks