This problem has already happened in many electronic devices in my home, almost every year. The solution is simple: to dismantle the machine completely and remove all traces of soil, ants and dirt.

Researching a little on Google, I found the repair manual of the Sony Vaio VGN FE31Z at this address: http://www.givemefile.net/smanuals/noteb...

Procedures carefully dismantling the equipment until the LCD. While performing this procedure, I noticed that the ants began to move from side to side, Laptop Keyboard leaving and entering the LCD.

The ants have focused on two points: the LVDS and backlight ballast.

I removed all electrical parts and proceeded to clean all plastic casing of the laptop, with water and detergent. While the coating was dry, I used isopropyl alcohol to clean the traces of soil. I applied a clean contact solution and the other in LVDS connectors.

I mounted the LCD, putting a little poison for ants to prevent future infestations.