Perfrom a complete power drain(Power cycle) by removing the battery and the AC adapter and pressing the power button for 30 seconds.
Next
Visit the manufacturer's website and download the latest BIOS.
The BIOS helps in managing the system process better improving the system's process management threrby reducing the overload of processes in the procesor in turn reducing the heat.
Click on the link below and choose the laptop's model to download the BIOS.
http://support.dell.com/support/downloads/index.aspx?c=us&l=en&s=gen
If this does not work then try to blow near the air vent using a hand held fan to clean the processor fan of accumulated dust.
if this does not work.
then the processor fan has to be accessed to get the fan cleaned. I shall provide you with a link to access the same.
http://support.dell.com/support/edocs/systems/latd800/sm_en/index.htm
This is the service manual for the product given. Kindly check the "system board" to access the main board to clean the processor fan. Also choose the microprocessor thermal cooling assembly to get access the cooling fan.
For the latter process I would recommend you calling the technical support because depending upon the manufacturer the warranty details need to be taken into consideration.
If the above steps fails to work then the Fan and the related circuitry needs to be replaced.
Kindly comment.