Uncheck under "Access Options / Client Settings / Advanced" - "Open last used database when Access starts"
We use for open the Database following Code in .Net:
Try dbs = DBEngine.OpenDatabase(strFilename, False, False) Catch ex As Exception MsgBox(My.Resources.Resource1.strAccessOpen,MsgBoxStyle.Critical, strAppName) End Try
This raise the Messagebox "The selected database is open..." if OpenDatabase failes.
Is no other database open, repair your Office / Access installation.