corrupted sounds mpc 2000

Hi all
I have and mpc 2000 for the past 10 years. Recently when i load a kit up from zip the samples sound ok for a second then when i press the pads the sound is all distorted, hums etc..Now i have swapped the ram because i thought it might be that, but the same thing happens even with the new ram cards installed. Is there anything else that might be causing this?
Thanks in advance

Check my post from a couple weeks ago: viewtopic.php?f=1&t=162298
There is a youtube vid in the post you can check for comparison. Does this seem to be the same problem you are having?