drum programm / doesn't play sound

allright, i have chopped my samples and made 4 drum programs with those samples which i spread always on 16 pads. drum1, drum2, drum3, drum4.when im finished with creating my sound i save my sound onto my card reader and turn off the mpc. next day i turn my mpc on. i put in my card reader and load my programs and sounds. it works smooth.
now, when i hit the pads for example from the programm drum1 some of the pads play the sound but maybe 3 or 4 don't play the sound. i think damn, where did the sound go then i switch into the programm menue and check the drum1 program where the sound is. i hit one pad which before didn't play a sound and what happens, he suddenly plays the sound i go back into the main frame and i can put all the pads and all the samples suddenly play again.

did someone have the same problem? do you know why this happens and what can i do that this doesn't happen it the future?

do you understand the problem that i have?? i know my english sucks and maybe it's a bit hard to understand what i actually mean.

hmmm that sounds wierd if it plays in the assign screen and not in the main screen. that's whats happening correct? sounds like a mechanical problem, short in wiring?...

yeah, that's right. when i load my program on the mpc maybe 3 pads won't play the samples in the main screen. then i switch into the assign screen and put the pad and it plays after i've pressed the button in the assign screen i can go back to the main screen and the 3 pads play the samples they're supposed to. really wired!

yeah that is really strange. prolly a functional problem or glitch. i guess just deal with it as long as you can make it work and if the problem gets worse and they stop playing all together hit up VST or Forat