Seems that the CDJ 2000 freezes after some time because of the Audio Sample Rate value

Hi...Since 2 months I switch from PC to a new MAC ( Retina version with SSD ). But since I switched to MAC I only encounter problems when I play. I load my tracks directly from RekordBox into the players( I dont use Itunes). At first glance everything works fine but after one hour the failures starts......I do not get any errors but what does happen is next :

1. the track stops suddenly...for about 3 seconds....continues for 2 seconds....stops again for 3 seconds and continues again for 2 ......etc.....

2. While dropping my track into the player on RB....the CDJ shows ...loading....... and keeps trying to load like forever..........

To solve this I switch OFF my player and switch it back on......then I can continue.....( not quite the solution I like )  :-)

This happens on random tracks and is not reproducable on the fly...it just happens.

My concerns is next : On my Dell PC I have a direct connection for my LAN cable. On the MAC this is NOT the case -> I need to use a LAN to Thunderbolt convert cable te get the connection with the CDJ's. Are there known problems to that ?

BTW..All my tracks are on a external disk. I run the latest RB version 2.0.3 and CDJ Firmware is 4.2

In the meantime I found out that my sample rate was to high set in RekordBox. I move the slider back to 320. Using 2 decks it works now.....but connecting to 4 decks I still have the problem. What is the Best Sample Rate to set in RekordBox nd how doe it influence tracks of 320 Kbps when the rate is set to f.i. 128 ? 

Please Advice or recommendations.