We've all seen it happen. Self-destruction. Career-limiting behaviour. Professional suicide. Some previously normal and capable IT manager suddenly starts acting strangely and destructively. He figuratively sets his hair on fire and runs around the building screaming of cabals at the top of his lungs. And we all stand by, watching the slow-motion train wreck, shaking our heads and whispering yet not knowing what to do.

If you are the supervisor of such a person, you've got a challenge on your hands. What do you do with a solid performer who seems to be going down a rathole and may take others with him? What do you owe the organization, the manager and the manager's subordinates?

The answer to these questions rests with the answers to a few more.

1. Why is this happening?

Of course, every case is different, and the reasons may not be immediately apparent. But over the years, I've noticed a few causes that seem more common than others. They include these:

Personal relationship disruption: Death, divorce and break-ups seem to top the list. The disruption of a family or relationship is a devastating experience. Grief, anger and confusion spill over into the workplace and can lead to behaviour that's confusing, in part, because it's unrelated to the work environment.

Didn't get the job: When someone is passed over for a promotion or a desired assignment, he can react unpredictably. He may try to undermine the person who did get the job, lashing out or perhaps trying to foment a coup. He may simply try to provoke others to confirm his value and worth.

In over his head: Let's face a sad fact: Some managers have been overpromoted. They rise too high or too fast for their own good, lacking the knowledge, skills or maturity for the position they hold. Some discover that they wanted the title but not the job. Most managers who are in over their heads know it. They can panic or react unpredictably. They see no way back to where they belong and can become unhinged by the experience.

Protest: Sometimes a manager sees his strange behaviour as a solemn duty or moral crusade. Rightly or wrongly, he may feel that a decision made or an approach taken is so damaging to the organization or so unethical that it requires an extraordinary response -- even a self-damaging one. He may realize that he is risking his career but be willing to suffer the consequences.

Wants to be fired: Sometimes a manager feels trapped in his job. He doesn't really want the job but doesn't feel free to quit or change. He may not want to walk away from the money, give up the status or face the wrath of a disapproving family. So, consciously or not, he hopes that you will solve the problem by taking the decision out of his hands.

Mental illness: Sometimes a seeming mental breakdown is just that: a descent into madness (that you hope will be temporary). Depression and substance abuse are common. No one is completely immune to the possibility of such illness.

2. Is this person's career in this organization salvageable?

You need to ask if the individual involved can be rehabilitated either as a manager or as an individual contributor. If given time and support, can he return to the mainstream?

3. Are there legal or cultural constraints on your options?