Game cartridges not showing up?

    Since I got the last  3DS update, my system won't read any of my game cards. It started out with just the normal DS and DSi cards, but then began affecting my 3DS games, too. Before it stopped reading my games, I would put in a game, it would read it, and then as soon as I started it, it would say to go back to the home menu. Any suggestions as to what this could be? My 3DS is from a couple months after the initial launch, but it reads downloaded games just fine. Thanks in advance for any help!