Strange system hang up ... Wonder why ....

EVer since I brought this whole NDS thing, I experienced twice system hanging, meaning that the system just hang while in the middle of the game. One time it hanged when I started Electroplankton., It hanged at the startup screen. (Nintendo is the bootup game) Another time it was hanged when I was playing J version of Wario touch. I completed the first level, and it was hanged at the saving screen. Fortunately the game was saved though.

Here's my observation:
- Hanging never happened when playing original games (Nintendo and Feel the Magic XX & XY)
- Never hanged on GBA games so far (but maybe it's because I RARELY play GBA games from SuperCard on Nintendo DS.

Guess I have to keep documenting the problem until the mystery solved one day.