Smartboard distortion only when laptop charger plugged in
One of our staff laptops distorts the smartboard image - only noticeable when the image is white, lines running up and down the smartboard image, a bit like on an old TV. This only happens when the laptop has it's charger plugged in, running on battery it's fine, no distortion.
I've tried a different electrical socket and charger but this doesn't help. It seems to be a combination of that laptop and that smartboard, according to the member of staff her laptop doesn't have the same effect in any other classroom.
Any ideas where I should be looking to sort this out?