These happened two or three times, at the beggining I tought : "is Microsoft Windows... everything can happen running it". But after a while I decided to investigate more, when I touched the back of the notebook to check whether any cables were unplugged or loose, I found that the notebook was very hot.
I thought "maybe it is an overheating problem" and I started to look for a temperature monitor program to run in my notebook on XP. At last I found that MotherBoard Monitor 188.8.131.52 , worked very well.
I installed the program, my wife started the "SIMS 2" game again and when the temperature reached 80°C (176°F) the notebook shut itself down, for self preservation.
So at first I tried cleaning the vents blowing air to them. But that was not enough.
I openned the two back compartments in the base of the notebook, and left them open. That helps but sometimes is not enough.
After some googling I found a device by Targus with vents.
Targus Laptop Chill Mat - Cooling Mat
That helps a lot.
So I made a home made laptop chill mat using two case vents and with this "gadget" the computer does not overheat.
As you can see my "gadget" is less beatifull but throws more air.
A few weeks later I bought a can of compressed air and blows the vents inside the notebook. That helps a lot, but one of my vent got blocked, So I had to open the notebook and move it with a screwdriver. After that the vent started to work again.