Just one of them things that happens. Usually on a busy weekend schedule. Presumably this being the last day of the holiday period with the Sunday schedules and the new series that's started caused the servers to overload. Note this happens more often on other sites when they run big events. Stars is built to cope with high traffic and usually does pretty well but this does happen from time to time.
I used to think that Pokerstars was the only site without crashes or disconnections , now that is not anymore . Ofcourse there have been similar incidents in the past , I think also a DDoS attack , but .... Ofcourse , in other sites , these incidents are multiplied by 1K or 1M times more lol