static interference with HPS and PC speakers

i have a 600 watt HPS in my closet, and a computer in my room. when the ballast is on, there is a static noise coming from the speakers. its ONLY when the ballast is on. ive even tried plugging my computer and speakers into a different circuit breaker by using an extension cord. same thing happens. when i plug headphones directly into the back of my computer, the headphones dont put out that static. any help?

It's got to be an electronic ballast, what brand is it?

One of the few problems with digital ballasts is the potential for interference with other electronics. My Lumatek came with an RF shielded output cord and it doesn't seem to cause any interference with my computer, speakers or cell phone. Depending on the brand of ballast you have, an RF shielded cord might be an option for you. Otherwise you'll need to contact the manufacturer for more info. Alternatively you can sometimes alter the frequency the device uses.

the interference is called 60hz hum. well its really whatever your ballasts output frequency is the range in which the interference is generated. remedy this with sheilded cables and you can isolate and shield the ballast itself, just be sure to let it be able to breathe. i just realized i repeated everything nullis said but made it alot more confusing. i think you can stabilize the interference with some sort of magnet, but that runs the chance of damaging any electronics