Distortion from Speakers

[unovis]

Hi all,

I get constant distortion noises from my external speakers - i.e. a pair of amplified speakers I use external to the laptop. Through trial and error I have found that there are two distortion noises:

- A high pitched squeeky noise which only occurs when the laptop is plugged in and charging.
- A low pitched buzz which only occurs when my external monitor is plugged in to the laptop AND plugged in at the mains

Notes:
- The noise has always been there, as long as i've had the laptop.
- There is no distorted noise from the laptop's internal speakers, or if there is distortion, it's not noticable.
- I have tried switching the speakers for a different pair which belong to a freind, and I get the same distortion.
- There is no distortion when listening to headphones.
- I have tried plugging the speakers directly to the laptop's headphone out jack, and the distortion is there. I have since bought an external USB sound card, and plugged the speakers into that . The distortion is still there.

The distortion is constant and not relatyed to the volume level. Um..... help!!? Anyone else had or heard of such problems?