buzzing sound with AC power

Archived from groups: comp.sys.laptops (More info?)

When the headphone out port (only audio out) is plugged into the stereo and
the laptop is hooked up to external AC power, there is an anoying buzzing
sound even when the volume is at min. I understand this is a common
problem? but was wondering if anyone knows a (cheap) solution. I have a
toshiba satellite M40.

Thanks, David.