Interferace from Mains power

[Karma Karl]

Got a Toshiba Sat L450D. All clean, bug free and up to date with everything. Gotta strange problem! When I have the mains power plugged in the speakers (internal or external) emit a very high pitch tone. I've got very sensitive hearing but definately not present when running on batter.

Sound is present regardless of what programmes are running. Or it nothing is running and the machine is just idling.

Any suggestions???

 

[Karma Karl]

Thanks "AntiGlobal"..... youre my hero!!
Feel sure this is the answer and am eagerly awaiting my new emi ferrite via that lovely world of ebay!