Big problem....

Hi everybody, and first sorry for my english...
So I have got some troubles with my MPC. I made a 6 bars sequence, 95bpm, with 4 tracks : one with a 3bars sample, an other with kick+snare samples, an other with a "second snare", and an other with the hh. When I play every tracks all together, if I play only one more single note, the long sample of 3 bars will stop....
I erased the HD, re-install the OS, no way, always this problem....
Can you help me
Thanks in advance !!!

go to the program of the long sample and hit f3 (param). then set the program to poly (in the upper right corner).

Already tried...