Causes
Action Replay video game cheating devices change the video game coding to allow players to cheat on their games. The available cheats are varied and depend on the type of game you are playing. In "Mario Kart DS," the available cheats range from unlocking all of the racing courses to changing the music that plays during a race. Making changes to the coding when enacting a cheat can have side effects in the game. One of the potential side effects is "Mario Kart DS" playing in slow motion. The slow motion effect may happen during a race, when navigation the menus, or both.
Solutions
When a cheat you entered using Action Replay causes the game to slow down, you need to restart the Nintendo DS. Hold down the "Power" button until the screen turns off and then press the "Power" button again to turn it back on. When you are given the option to select the Action Replay cheats to use with the game, do not select the cheat code that caused the game to play in slow motion.
Prevention
Finding which codes cause "Mario Kart DS" to play in slow motion is a matter of trial and error -- and research. Websites with Action Replay codes, such as Neoseeker, may inform you that a certain code causes the game to slow down when you use it. Some codes that cause slow motion play as a side effect have alternates you can use instead. The alternates provide the same effects of the original cheat code without the side effects of the game slowing down. One of the features of the Action Replay is the ability to delete codes from memory. When you find a code that slows down game play, delete it from memory so that you don't accidentally use that code at a later time.
Considerations
Though playing "Mario Kart DS" in slow motion has its drawbacks, it also has some advantages. A slower game allows you to react more quickly to obstacles in the course. Slow motion also gives you the opportunity to study the tracks and look for secrets, such as shortcuts built-in to many of the courses to give you an advantage over your competitors.