What I am reading here I think needs some clarification.
Unless you are very comfortable with your skill when working with electrical panels, before you work with or remove any breakers, you need to shut off the main breaker!
Dodgeman is correct in his assesment but, before you check the wire to see if it is getting hot you need to make sure that you follow the basics of electrical safety, you are not wearing any rings or watches and that you do not touch any bare wires, ect..
I know that this may sound very precautionary, but, I want to keep you around for awhile and I'm sure Dodgeman wants to as well.
When in doubt, call an electrician! I would rather pay for a service call that have my family collect my life insurance.