Not many people knew of his Twitter account, but I did. He would post crude remarks about the manager not listening to him and how he should be the manager, often using the initials of the manager when he insulted him to be careful and not be accused of slander I guess. I would often hear him in the office talking to himself, swearing under his breath and mashing his keyboard. You could tell it was getting to him. He was on-call 24/7 but apparently wasn't adequately paid the amount he should have been for someone who was expected to fix something at the drop of a hat.
One day he came in and sat at his desk refusing to do any work. He just sat there and then the manager confronted him and asked why he wasn't addressing his list of high priority tickets that he had and then the guy lost it. He didn't get violent, but he started yelling at the guy and the manager was a well-built guy (sorted of sounded and looked like Arnold Schwarzenegger) who I wouldn't even dare cross. After yelling he just walked out and never came back.
Of course my manager reported the incident to some higher-ups and then it was revealed a couple of days later he was in a mental hospital as he had a complete breakdown (he apparently drove himself there). I didn't know him that well, but I went and visited him after finding out where he was. He told me that it all built up; he was being blamed when things went wrong and weren't done on time and not being praised when things went right and were delivered within unrealistic time-frames. His girlfriend had also left him the day prior to the meltdown, he said she was unhappy because he was never home and when he was, he was always fixing something remotely or had to come in to fix something.
I have a feeling this kind of thing is a lot more common than we can imagine.