toshiba a300 sound problem when plugs into mains

hey guys

my gf bought a a300 toshiba

have it plugged into a klipsch 2.1 home theatre system thru the head phone jack
3.5mm -> 2RCA

everything runs thru it no problem - tv, dvd etc

but when plugged into new laptop and when turned up you can hear a static sound thru the speakers

normally in my experience its because a power cable isnt grounded correctly on the ac adapter's plug that goes into the power socket or the wall socket itself or multi power board.

any idea? have tried changing laptop so have eliminated the laptop power socket being faulty and also checked the 3.5mm headphone out by plugging in headphones at high volume so the headphone out is fine because i heard no static thru the earphones

any ideas? i was going to try change the 3pronged plug the half that goes into the ac adapter ffirst but dont have one spare

wondering if this is a common fault with these units ??

anyh help would be appreciated thanks

 

also forgot to mention have plugged the power adapter into 3 different sockets and get same result . thanks

 

I've had this problem when directing digital audio from an HDTV to an external amplified speaker. The cure is to select CD as the sound source.