I need your help my freinds

i use routerboard RB1000
and i face a new problem when i moniter on the trafic on real interface i see a drop for 5 sec and i dont know from where may u help me plzzzzzzzzzzz


this is a screenshot

you have to upload the printscreen

http://forum.mikrotik.com/t/pptp-trafficproblems/34749/9 ?