Hi .. I just cleaned only the heat sink ( I didn't remove and touch the processor either) of the processor due having heavy dust on it, Since we do not have a vacuum cleaner I decided to use small paint brush and it actually really soft then eventually after I cleaned it I put back the heat sink including the fan properly and connected all devices on it and I on the computer. the problem is the computer unfortunately didn't work. but the keyboard is working i think b'coz what i have noticed the numlock, scroll lock and caps lock is lighting. and the DVD ROM. what do you think is the problem ?? thnx. . what should I do to fix it.