After three days of disruption that began on Christmas Day, Sony's PlayStation Network is back up and running. Sony said that the outage was caused by artificially high levels of traffic on their network, resulting in disruptions to online gameplay and connectivity to their network. The hacker group, Lizard Squad, has claimed responsibility for the attack. Microsoft's Xbox Live network also saw outages on Christmas Day however Xbox Live was working again on Friday despite some ongoing issues. Sony said on Sunday that heavy traffic could still be causing problems for the 56 million people who use the Playstation Network. Whalen MacHale reports for TheStreet from New York.