I remember a DSL customer who had a really hard to diagnose trouble with his high speed internet every evening at the same time. Once we discovered it was electrical interference, he immediately blamed his ham radio operating neighbor but when we called the operator up to politely ask about his usage habits, he was quickly dismissed. However, he helped us discover that it was actually a frequency sometimes put out by powerful welding equipment. The real culprit was his other neighbor working on restoring an old farm truck frame.
