Mystery sound interference.

I have a cheapy set of 2.1 speakers.

(http://www.walmart.com/ip/Cyber-Acoustics-CA-3090-Multimedia-Speaker-System-CA-3090/25566557)

I've had them for a while and I didn't have any problems until recently.

After building a HTPC and waiting to buy a new tv for the living room, I had those speakers connected up to the PC. I would get strange interference that would be affected by motion on the screen, like when I would scroll webpages etc.

Now that I have the TV, I connected the pc to the tv via hdmi and connected the 2.1 speakers to the TV via the headphone jack.

I get the same interference that I had before, and again it seems to be affected by what's on the actual screen.

So I thought it must be the speakers, but when I plug them into a phone and an ipod, they sound perfect.

Can anyone explain this?

Additional info. Now that the speakers are at the TV, I used a 3.5mm male to male jack extension and connected it back to the computer and I had almost zero interference.

Also, something I forgot to mention, the speakers worked fine when they were next to the computer a few weeks back, it was after I relocated the desk the problems started.

If they are close to the TV or monitor that you where talking about, move them back some (a couple feet) and see if it still does it or if it goes away or lessens. Also make sure they are not next to the PC, could be something doesn't have good shielding or the chokes in the speakers aren't the greatest.

If you have another set of speakers, better quality, hook them up in same spot and see if they are doing it as well. If not then the cheaper speakers aren't the made with very good quality part or engineering. If the better quality ones do it also then something isn't shielded very well in the PC/TV or monitor.

My money is on the speakers.

Took them to the middle of the living room, plugged it into the tv, same humm as loud as before,

Turn up the volume on the source devices and lower it at the speakers.

I did, however even with the tv at full volume it's barely loud enough, turn it up a little and the interference becomes noticeable.