Upload your .sav mate for someone else to hopefully (I don't own an AK2i but can try on the numerous other carts I have) try and see whether or not its a game problem or µSD problem.
Also, are you playing the (U) or (E) release? Is it a clean rom? Blah, blah, blah...all the atypical questions which come from such an undetailed help/bug problem on any cart lol