Help in stoping speaker buzz

When I am listening to digital music on the cable music channel I have a buzz in my center and rear speakers, but the buzz disappears when I listed to normal CD's. How can I get the buzz to go away on cable music?
I have the same problem with my DVD when hooked up to cable so I have to disconnect it when watching a movie thru my system. My dealer told me to get a ground isolator or something like that. It goes between your cable and the source. Maybe more knowledgeable posters can give you more detail. Good luck.
This is usually caused by a difference in voltage from your system's ground and the ground on your cable. It is not unusual for the cable company to have faulty grounds. You should complain to your cable company and they will come out to inspect their cable. There are ground isolators that will stop the buzz but they sometimes degrade the picture quality.

This is a very common problem and any knowledgeable dealer in your area should be able to assist you.
I had the same problem til I bought a ground loop isolator. Everything was great til I went with digital cable, then picture quality was terrible. I had a choice, buzz or bad picture. Currently, the ground loop isolator is out of my set-up, my cable runs through my Monster HTS5000 power center and the buzz is not audible to anybody else but me(isn't that always the case). My ultimate solution is this, whenever possible, VHS, DVD, or during CD listening I completely disconnect the cable from my system, again, nobody but myself hears a difference. Actually, the only difference probably is that I know there is no chance for interference. To summarize, you may have to expirement with a few different solutions til you find the one that works for you. BTW - I had the cable company come out and re-wire from the pole and using the same ground as my panel. Until I can afford to have a separate 2ch system and HT system I will always be listening for the ghost of the once present ground loop. Maybe I need a therapist, hehe.
I guess I'm just lucky. Years ago when the cable co called it"DMX-radio" / This was a separate box,and the music info was on the remote's screen. I never had any problems. This "box" had a coax dig.out.You got your 30 channels + you had 10 tv stations in digital/ mtv, hbo, ppv,etc.This was the bench mark when I switched to Sat. I now have a coax on my older Sony/ Direct receiver. I had the toss linc replaced with the coax.It is "Quite Good" indeed! / Back to Cable;Their box with the coax,out / now only gets the music stations. (The coax is not active on the tv stations) Wonderful Time Warner!!. I have the Chang 1000,/isolated lines/ and "good" power cords. I think this is what it takes.
I had a speaker buzz coming from my center & surrounds; it only occured when the pre was in pro-logic mode (stereo, mono, "stereo surround", Dolby Digital, and DTS modes were fine). I was able to reduce the buzz by placing a cheater plug on the pre (3 prong to 2 prong adapter).
I then placed a cheater plug on my Genesis Digital Lens and the buzzing vanished.

I would try cheater plugs first and then a cable ground isolator.