Hello, I've been having problems with my hard drives. During computer operation (boot up or use) I sometimes will hear a hard drive "click" which is followed by the computer freeze. When it initially occured, I thought my hard drive was dying. I was still able to boot if I tried multiple times until I did not hear the "click" and it would run for a while without freezes until the next "click". The computer would run without a problem for a long period of time. Days. If I shut down the computer I would have a high chance of getting a "click" during boot up. Anyway, I replaces the drive I had with another drive from the same manufacturer. It was a Western Digital 500GB drive. Couple of months later, I started getting the same problem. During this time I had switched from Windows XP to Windows Vista. At this point I thought I just got unlucky with two unreliable drives. So, I got a Seagate 750GB drive. Two weeks later, the same problem. I don't hear the same type of "click" but I do hear some short noise from the drive which is followed by the same computer freeze. So, I guess the problem is not with the drives. But what could it be? Is it the power supply? Is it the mother board? How could I identify what the problem might be? Replacing a motherboard is too expensive so I'd like to identify the problem so I can replace the problem part only. I've had the system for a while and don't remember all the exact specs. Here is what I know: Motherboard: ASUS PC-DL Deluxe with 2.8GHz processors. Power supply: Enermax. I searched for its number CNS13438-Z and came up with 220W. Hard drive: Seagate 750GB internal DVD-RW: internal Video card: GeForce 7800 GS Thank you for any help.