Unless you have a mailbox overrite or recolors, this is a know problem with AL. The big mailbox reverts back to the default single mailboxes. Pescado has a fix
here, although it only fixes some of the known issues and it is not the "official patch". As for the game unable to start, try deleteing your "Groups.cache" file every so often after gameplay. Located in "My Documents\EA Games\The Sims2".