Overheating

Frequent overheating will damage the motherboard! Here is an expanded article on heat and laptops.
Symptoms:

The laptop starts beeping, freezes, restarts by itself or shuts down after it has been on for some time, typically 10-15 minutes or more. If you start it again, it does the same thing after just a few minutes.
Troubleshooting:

Most laptops overheat because the fan intake is blocked either from placing the laptop on a soft surface or by dust. In either case you will need to let it cool down before turning it back on (may take up to 30 min). If you suspect that dust is blocking the fan/heatsink, get a compressed air can and try to clean it now (that will cool down the laptop too).

Sometimes overheating is caused by a fan malfunction. If the fan is completely stuck, the laptop will show an error message immediately after starting. However in rare cases the fan’s fins are just loose or broken and won’t move enough air to cool the laptop.

In either case you should try cleaning the fan(s) and heatsink(s) with compressed air. That is best done outside, as usually there is a surprising amount of dust accumulated in there. If the laptop continues to overheat, you will need to bring it to a repair shop.

Also if you have dropped the laptop, the screws holding the heatsink may have broken off. In this case the laptop will overheat in just a couple of minutes as the CPU has lost contact with the heatsink and is not cooled at all.