When an user opens Office files such as .XLS or .DOC over the
network shared drive, users are getting the error the file is already
in use, would you like to open in read only mode.
Files that are being accessed are not password protected.
This issue is happening for many users irrespective of the file being
opened (excel, word etc)

We are currently running Windows XP with SP2, Office 2007 in our
environment.
I have verified the modify permission is fine (and I have verified the
other permission settings) and the issue was not there until we
upgraded to Office 2007, we reverted to saving in 2003 format for
Excel and Word but it had no effect. The DDE check in excel had no
effect and there is not a similar setting in Word (that I know of).
Re-registering is not the fix either as it happens on multiple
machines, it does not happen consistently either. If I go to the
server where the files reside, I can see the lock and the lock is on
the owner file and not the actual file. This is not an issue where
legitimately multiple users have the file open. Any other ideas?