black screen instead of login screen?

i used the duel network to play yugioh online. I closed the window, and was given an alert that i'm leaving the duel network. so once i closed the window, i needed to get back on for something, and i could not. i tried to access the login screen, but in vain. all i got was a black screen. nothing else. the page loaded completely, but the screen was black. this happened on 2 of my mac computers using safari and i could really use some help. thanks