On Mon, 1 Aug 2011 14:57:28 +0100, "N_Cook" wrote:

Powered speaker works fine with clean audio feed but get it connected to the
audio out of the owner's laptop and it drops into some undefined error mode
killing the speaker output and display/,switch off, restart and repeats.
The powered speaker has an unused MP3 connection and tuner and laptop has
wifi etc, unused for audio feed. I suspect some sort of RF is being
conducted down the audio leads. Other than passing 2 or 3 turns through a
ferrite ring - any ideas?

Does it do same when laptop working from battery?
What about just with the common connected?
Make up extension lead with rf filter to determine if anything
conducted.