Samples cut out when recording to a track. help please

Hi to all at mpc forums!
im pretty new to the world of mpc so this probably wont make much sense.
Ive just upgraded to jjos1 on the 1k and im having trouble recording samples into my tracks as they keep cutting out at random intervals when i play a sample that is longer that a second or two, but when im not recording the sample plays right through,and it only seems to do it if i already have a beat going eg. snare, kick, hat, fx etc. Its like theres a limit on the amout of sample i can use.
I never had this problem before i upgraded. Is there something im not doing right????
any help wuld be appreciated.

Peace

niceone for the links Lampdog, Ive changed all my pads to mono but it hasnt made much of a difference at all.
Everything else about the os1 seems to be much more advanced and easier top use, except for the voice moniter, I dont get how im meant to program a a full track/song using only a few sounds? i want basslines, synthlines crashes hits, fxs, etc. whats the point of having 64 tracks if you cant use them all? With basic akai os i used to layer upon layer sounds and never had any problems at all. I thought the jjos1 was meant to be better, and it is!!! apart from this hickup, i hope im missing something simple!? is this just the way it is with os1?

thanks