Weird attack delay ?

I have a casio Privia s1000 and am experiencing an odd delay when striking chords and notes between the left and right hand. Compared to my keyboard's internal engine vs pianoteq, PT introduces an odd delay such that if I were to hit C2 with my left and play a C major chord at C4 with my right, I will ALWAYS hear a difference between strike times of my left and right. I have also noticed that upon striking the keyboard, as long as the modeler is active, the delay then disappears and things sound like they are hitting at the same time. But as soon as I let go of the keys and let the modeler go back to 0% CPU, when I strike both hands there is most certainly a delay between the hands. THIS IS DRIVING ME CRAZY. THIS IS NOT A GLOBAL DELAY RELATED TO SAMPLE RATE (2.4 ms @ 128)

There most certainly is no delay when using my Casio's internal engine and have verified this over and over again. I can try and post an example later in the day. Any one else experience this odd behavior? I hope I explained it well enough.