While Senor Cruz is still going on about a power failure being the culprit, it struck me that everyone, including me, has been assuming this refers to the big electric, coming through the wall (230V, 440V 3KV or whatever). If any of these fails, one would expect UPS to immediately take over ( a "no break" supply).
What about the internal power suuplies driving the servers etc, ie the bits that turn the incoming electricity into 5V, 12V, 24V etc? If you let the smoke out of these, no amount of UPS back up is going to help.
Just a thought.