Reply to Akai APC40 and traktor pro, full midi maping incl. led lights and led rings work

Hello,

I have an APC40 and i did all midi mappings in traktor pro. I made leds on clip lunch buttons, and even led rings to work in pan/volume stile.

I have an M-audio Fast track pro an HP notebook with 4 GB ram, and dual core 2.2GHz (XP sp3)
Everything is working fine except i have audio crackling on low latencies...
if I go to 10ms i hear crackling. On 40ms and more sound is perfect.
I believe the problem is when traktor sending midi to APC. Those output midi messages for controlling leds on APC. When I turn them of everything is ok.
Is there anyone with same or similar problem?

Also if there are interested in my mapping i am happy to share...
Apc is mapped for all things, looping, hot-cueing, internal mixining an eq...

sorry for my bad english