issues with tracks on mpc 1000

i have several tracks recorded on my mpc. the problem occurs when i unmute all of them to hear the song playback. if one track plays the others will break up (pause). i can play the tracks individually and they sound fine. just note when they are unmuted. is there a setting i need to change? thanks.

This usually happens when all the tracks are the same.

If so, break them up. For example have 1 track play kick, 1 track play snare, etc...