I installed (a few years ago) an extra light in our closet that is just run from a jumper to the existing light. I can have that light on as long as I want, but the moment I turn on my TV or computer (on the same circuit) it trips. I can have my TV or computer on at the same time, but the moment I (or my wife) turns on the light in the closet the breaker trips.
I installed the light using the same 14 gauge cable the house was run with (irritating, wish it was all run with 12-2 or 12-3) and made sure the connections were secure and all connections covered by wire nuts.
I'm at a loss at why this keeps tripping. I've replaced the breaker twice and it will run fine (light on and TV on) for a couple months and then it trips again.