OK, this is a problem I am experiencing from the last few days. My PC starts normally, but many times when I work, my HD stops working and the PC get hangs. If I wait for few minutes (5-10 min), then the HD again start working and the PC began responding. I think the problem is with HD because when PC get hang the light of the HD stop flashing. I also have lots of power fluctuation in my house. So, Is this a problem with my HD or my Windows installation is corrupted.