Dell inspiron 1525 computer and charger gets hot ?

i have a just over 1 year old Dell inspiron 1525 which is beginning to play up.

A few months ago the laptop was overheating and switching itself off. I purchased a usb fan cooler and this appeared to do the job until recently.

The charger stopped working and when i felt it it was very hot.

I bought a replacement charger and this overheated and stopped working after about a week!

I plugged a colleagues charger in and the light on the charger switched off when it was plugged in.

Does anybody have an idea of what the problem might be and how easy it is to have rectified.