The reason is because Forumotion, the site that WOTN is connected to and runs on, is replacing some old servers and adding some new ones. When they're done, WOTN should run faster than ever and have less problems than ever.
But so far they are having slowdowns and the typical errors any website encounters getting things to work.
So just be patient! This isn't a permanent problem. And most of the time if you wait about 2 minutes after WOTN refuses to open it comes back up.
I'm glad we know its not Forumotion crashing to its death or hackzorz. So this'll probably be fixed really soon.