strange cuts in middle of recording

Hi guys,
i have this problem in my recording sessions and it is driving me crazy !!
when i am recording suddenly there is like a “cut” , for 2 seconds with strange radio-tv flip channel sound ,
the thing is, you don’t hear it while you record… no no … only after…when you start edit,
so it is making the problem even bigger !!

any body got advise for me ?
i can also send an mp3 file if you want to listen to the problem.

i am using :
cubase 6.5
Rme fireface 800
mac user - Imac i7 (strong and improved and cost like hell ) osx 10.9.5