Hi all.\nI am brand new to this forum so please excuse me if I am dragging up an old/resolved problem\nI recently decided to rescue an old Toshiba Satellite L45 laptop just to save it from going to landfill. I am actually using it to build some jukebox software. It did have Win. Vista installed. I have now installed Linux Mint (32 bit latest version) which is a great success.\nI have however got one problem. The laptop produces a fairly high pitch whistle which I had put down to the inverter.\nNow I am not sure. The whistle disappears for a short while if I reduce the screen brightness, then reappears. It is not there if I unplug the power supply and run on battery, even if I turn up the screen brightness to 100% When I get it to disappear for a while it will come back if I plug in an external USB drive, again only when using the mains adaptor, and not when on internal battery. It is still there if I connect an external monitor and switch off internal screen.\nI just can't think it through.\nAny ideas?