Possibly one of one of the codes that was entered was incorrect or it may simply be something wrong with the action replay itself.
it will say this because you have too many codes in delete some that you dont use
today this happened and I deleted some codes and it is fine
i have the same probleme and I just try to close my DS and remove my AR and then you turn on the ds with the AR in and it work (i m sorry I m french . . .)