I would say it's either a bad lamp with a short or a sheer coincidence, but definitely seems a problem with your box. When you demand power on a circuit with a bad connection at the breaker, you create an extreme amount of heat and arcing. This however, does not dictate a panel replacement based on the information you've given. Can you describe as clearly as possible, the picture of what you see wrong inside the panel. For example, the connection of the wire to the breaker, or the connection of the breaker to the panel bus, or the connection of one of the main feeders to the panel. Also, the brand of panel and a rough guess on the year it was installed would help. Good luck...this information will allow us to give you further assistance.