I am using a Sony VAIO vgn-tz2500 laptop, and it's overheating when I watch Flash movies (Youtube etc.) and it starts to lag. I had a computer before that had problems with overheating but it shut itself down because of overheating, while this laptop doesn't! I dont know what is the problem here - is it about the cooling system or bad drivers, a virus? How do I fix this?
Your notebook is equipped with Intel Core2 CPU that has a builtin thermal control. When the temperature of the CPU grows too high it just decreases the core frequency, thus reducing the power dissipated in a unit of time. Under normal circumstances of course it should not be overheating by running at full computational load, so you need to check the cooling system (clean the fan, e.t.c.)