You also have to look at the server end, client/server (especially if accessing Novell), and possibly the settings for the desktop operating system.
For example, if you store the database on a server, then you have to look at record locking on the server and the client / server.
If the database is located on your local hard drive, then you may have to close other files / applications before opening the database.
Hint:
If the problem is occurring on the server, copy the database to a local drive and trying opening it. If the database is located locally, copy it to a network drive and try.
If the problem persists, then it may in fact be a problem with the database. If the problem goes away, then look at the operating system issues I mention.
From "past lives", look at Opportunistic and Pesimistic Record Locking on the server.
Richard