This can also be the result of a damaged neutral at the transformer, or the incoming line. It can result in a weird series/parallel delivery problem, where the neutral is creating a bridge between both of the 120V legs. I actually had a customer who had reading as high as 156V to ground in his home, after the neutral on an underground service feed had developed a lot of resistance. The power company lied their butts off, and denied responsibility, until I met with their engineer, and showed him some of the readings.