My computer froze when i was using it. When i tried to reboot it, it did not start at all...i opened up the chasis and saw the CPU fan not working. Actually it looked as if the CPU fan is trying to spin but something is blocking it(propeller has slight movement). Shops are asking ridiculous amount to just find the fault. Any idea where i could start troubleshooting? I have been using the computer for couple of years without any problem.