The release of Final Fantasy XI and the official launch of Square's PlayOnline were hampered by a lot of problems. While at some times playonline.com simply wasn't accessible anymore due to issues with the game servers, there was a more severe problem with the Web Money and credit card services. The servers which handle the verification of credit cards and Web Money didn't work properly, displaying wrong information even after the cards were debited. In an apologetic statement, Square mentioned that the entire service was down for about one hour.
Currently the company is working hard on solving the remaining problems, in particular the accessability issue.