Instructions
Double-check your codes and make sure you are correctly entering them into the Action Replay. Action Replay codes are a combination of numbers and letters that must be entered in a specific order. One misplaced number or letter could cause the code to fail and not appear when you load your Nintendo DSi game. Use a site like NeoSeeker to find a listing of proper codes for Nintendo DSi games and the Action Replay.
Turn off all the codes you have previously entered into your Action Replay (if your Nintendo DSi game is locking up and freezing). Return to the main Action Replay screen and enter one code. Load the game. If the game properly loads, return to the Action Replay menu and add one more code. Repeat this process until you identify the code that was locking up your DSi game. Do not use that code when playing the game.
Download and install the Action Replay firmware update for the Nintendo DSi. Firmware updates fix issues, adds support for new games and codes and generally makes the device more pleasant to use. Download the firmware update from the Code Junkies website and use the Action Replay computer software to sync the firmware to your device.