I bought a used DS Lite in order to play the small percentage of DS games that are region locked and won't play on my DSi XL.

I know the cards are good, but this DS Lite won't recognise the game card if I insert it and it's switched on already - yet if the card is inserted when the power is off and then I switch it on, it all works fine.

Does anyone know why this might happen - is the unit faulty?