I'm having a couple problems with my R4. Its freezing whenever im playing Metroid Prime Hunters and Mario Kart. Metroid usually freezes when im coming back from closing my DSlite and playing for a little bit after that.. Mario Kart doesnt freeze as often. Also, sometimes the DS doesnt recognize that the cartridge is in side. Is this an R4 problem? or a microSD problem? im using a SanDisk 2GB microSD card.