Bob Pittman and AOL Time Warner. Jean Marie Messier and Vivendi. Jill Barad and Mattel. Dennis Kozlowski and Tyco. It's an all too common scenario. A great company breaks from the pack; the analysts are in love; the smiling CEO appears on the cover of Fortune. Two years later, the company is in flames, the pension plan is bleeding, the stock is worthless. What goes wrong in these cases? Usually it seems that top management made some incredibly stupid...