Why would an ethernet cable cause your speakers to buzz when plugged in?

[Obsoleet]

Does anyone know? I had this today and decided to troubleshoot starting with first things first by simply power cycling my router and dsl modem and it went away.
I thought about getting an inline ground adapter for my cat5 cable but don't see why if there was voltage coming across my network why it wouldn't take the quickest path to ground?
Which definitely isnt coming across the network, thru my mainboard causing a strange sound issue?

 

[jaqie]

EFI and/or RFI.

 

[spidey07]

Also called ground loop hum. You've got a bad ground somewhere or possibly your cable isn't grounded properly when it enters your house.

 

[Obsoleet]

Ground loop hum, ok. I read a few webpages on this, should I have an electrician come and make sure our wiring is up to code?

 

[Obsoleet]

and why can't I reproduce it now?? :/

 

[Obsoleet]

Ok, I found out how to reproduce it.

First of all these are powered Dell lcd speakers, powered from the LCD.
I did some messing around and the sound is similar if you put the end of the speaker plug onto your finger. I noticed the buzz only exists when I unplug EVERYTHING from the back of the PC and plug in the speakers. Of course they have to be powered on and they then buzz.

As soon as I plug in the power cable to the PC or the DVI, it goes away completely. Plugging in the ethernet cable makes it louder yet actually, which I found strange.

I don't understand why my speakers would buzz louder when nothing else is plugged into my case? Is there a problem with my speakers leaking juice thru the plug when they're on? Or is this just normal for crappy speakers and the ground in the power cable takes care of it?

I'm thinking I need new speakers and these have something wrong with them. Looking forward to your replies!!