cannot open any titles when opening them up.

Hi!

One day I was bored and wanted to use my dsi. it was working as normal until I opened a game, it gave me the "An error has occurred" and i was all like: ok, maybe it is just the game, so I try system settings... same thing. i ended up trying every application and they all gave me the same error. i tried L+R+UP(D-PAD)+Start and i got the same thing. only at one point o tried a application one more time and it worked.... i tried all the other applications and they worked. turned off the system and then it stopped booting up applications. anyone know how to fix this?