If she, like you, lives in Australia, it's the middle of summer, your moms computer is probably just struggling to keep up with the heat. You guys just had to add another color to your heat index, after getting up to 52c last week (125f). Is your AC running, or is the computer in direct sunlight? Try putting it in the shade, there's not too much else I can think of that would help the ventilation on a Mac. And that big black screen can absorb a lot of heat from sunlight.