using DAO on a password protected workbook
 

I have written a large add-in that access multiple files with DAO. The files
are protected so they are opened with the password before attempting access.
The Add-in is meant to be multi-user (inquiry only if not 1st user) so it
recognises if its already in use and opens the files as Readonly for 2nd and
subsequent users. DAO appears to work perfectly. However when the 1st user
closes the application, DAO fails for the other users even tho the files are
still open as readonly. The error is the usual "cannot decrypt file". Can
anybody help please.