>>Someone in our community (Dan Freeman, maybe) used to talk about some corruption that only occurred at a certain time of day. After a long time, they figured out it was when a vacuum cleaner was being run or something like that.
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>That may have been me. We had a pharmacy customer whose indexes would get corrupted several times a week. We eventually discovered that on the other side of the wall the computer was near was a medical clinic's X-ray machine. I doubt it was X-rays but likely a power surge from the machine.

In two medical institutions we had trouble in such places. One was an x-ray, the other one was a lab and we still don't know which machine was the cause.