DS lite problem

[leon_belmont]

Hi guys ,my DS lite just start turning off and back on itself in the middle of the game,not with all games but a lot of them. The list is below of my most favorites which it turns off and back on:
Dragon Quest IX
Dragon Quest VI
Dragon Quest V
Castlevania Portrait of Ruin
Castlevania Dawn of Sorrow
Teenage Mutant Ninja Ubisoft Version
New SuperMario Bros

I am using a R4DS (plays NDS roms) ,but it played fine until now ,so what are your advices, battery problem? cause i tried with a R4DS of a friend and still the same ,so i dont think is the R4DS.
Final question
Battery problem or console problem ?
Thanks in advance.

[leon_belmont]

thread update, i managed how to bypass turning off and on in dragon quest IX ,by doing quicksave every min until i got to the first real save and the game plays fine now. Unfortunately this doesnt work with the others games.