We're using the Microsoft Access workgroup file (groups.mdw) for more than 25 users. The problem arises when we attempt to add a user to this workgroup file while there are users logged in using it. After adding the new users to the workgroup file, if user logged out and can't log back using this workgroup file. I didn't get a screen shot of the error message that appeared, but it said something like "workgroup file is in use".