I have a wall plug with two outlets. Anything plugged in the top half blows the breaker. The bottom half is fine. The box is one of 5 in a circuit. There is nothing plugged in to the other 4. I removed the plug and checked the connections on the wires leading into the box. There is one wire coming in and one going out of the box. They are tied together with what appear to be good connections with a pigtail coming out for the outlet. I changed the outlet itself, thinking something may have gone wrong with it, but have the same problem. Any suggestions?