MPC 500 MIDI PROBLEM - out of sync, off beat

[roughgear]

Hello there,

I have a big problem with my MPC 500.
If I connect it to Logic it does the weirdest things:
Sometimes starts with Logic and sometimes not at all, sometimes stops in the middle but always plays like it was totally mixed up.

I did two videos for the german distributor - maybe someone of you has a solution:
The first video is an empty Logic project with a metronome at 120 BPM.
The MPC starts and I add the metronome after 14 sec. The two metronomes should be in time but they are rather fighting agains each other. The MPC stops after a few more seconds by itself!

Second video is a song with drums (only drums activated) with easy Bass Drum in the beginning that totally falls apart after the Snare and Hi Hat start to play.

mpc500-midi-problem - YouTube
mpc500-midi-problem2 - YouTube

This happens on my two computer setups.

An iMac with Edirol Midi Interface and a Mac Mini with Midi via Motu Traveler Interface
Mpc: 128 MB Ram - Version1.31
slave-on/soft thru-off/midi channel set in track param/
Logic 9: Transmit MIdi Clock and MMC also checked with mtc

I'm clueless - it's a brand new machine, I just got it from the distributor as an exchange for my old one that was whining like crazy.
The new one is silent but can't handle midi.
Thanks for your help!