Sound buzz and shuts off

Ok first off I'm using a Sound Blaster Xfi Extreme audio I believe. I currently use a headset as my source of sound. So I'm on my computer and sometimes my headphones emit a buzz sound of different frequencies for 5 seconds and then my sound shuts off. Meaning no sound works, I can't play videos and music won't play in itunes. This lasts for about 5 or so minutes. Can any of you tell me what is wrong? I have used multiple headsets and speakers and it happends still.

 

Totally out on a limb ...
Could the different tones you hear be the surround sound test mode....more like a white noise-sends about 3-5 sec test to each speaker l,r,c,rr,rl,sub

 

nooo. It's a sharp buzz. screech, buzz, and so on. Could it be my soundcard?