Overheating Computer!

I am trying to fix a problem on a Packard Bell iXtetreme, It turns on and everything ok, but after a while it shuts itself down I think it is overheating as it runs pretty hot after a whole, Does anyone know how to stop this?

Here are the specs: CPU TYPE: Intel Pentium 4 CPU
CPU SPEED: 2400MHz
CACHE SIZE: 512 kb
MEMORY: 1024mb

Help will be much appreciated.