My computer will not start up. I have tried everything, swapping power cables and pluging into the wall. At the back of the CPU the power pack you plug the cable into just makes a clicking noise and a green light which is normaly on just simply flickers rapidly.

Does anyone know what's wrong with it? I even cleaned the little dust that I found in the machine and re-plugged in all cables to ensure against lose connections.

Is this a laptop or desktop? If it is a laptop, you may have a bad AC adapter (the box with the cable attached that plugs into the back of your laptop). Also check where the cable plugs into the back of the laptop. Is the connector inside loose? This problem could also be caused by a shorted battery or a damaged cable between the adapter and the laptop.