We have a 4 node Meridian Mail 12 modular options voicemail system operating with a Nortel Option 61C. Sometime ago we begin to have a problem with Node 3. we would get complaints that some users were unable to access their voicemail boxes. Upon investigation we would find that the hard drive on Node 3 would be shot. We would replace the hard drive and restore the user data. The system would operate ok for around 30 days. Once again we would get complaints that some users were unable to access their voicemail boxes. Again we would find that the hard drive was defective on Node 3. We have replaced this hard drive at least 4 times within the last 4 months. I might mention that this is a DC operated system. The weekend that this problem began we lost a computer and a radio system in the same room where the voicemail system is located. Both of them were destroyed as if from a power surge. Does anyone have any suggestions on what might be happening to these hard drives?