I can't emphasise enough, try to use your computer only when it is reasonably cool, even if that means first thing in the morning. I tend to stop when my room reaches 30C/86F, but even that's pushing it. I would prefer no greater than 25C/77F when possible - don't forget the insides of your computer will be a lot warmer than the room temperature.

If your computer gets too hot you can do irrepairable damage to the motherboard, or worse, the hard drive.

Make sure you take time to do back-ups every so often in case something does lock up along the way, that way you won't have lost the half chapter you were working on :(

If you can, switch it off in between uses so that it spends as little time as possible generating heat of it's own.

Penny