Update 5:00 p.m. PDT: Maintenance has concluded and Diablo III is now available for play. Auction house maintenance has concluded, as well, but commodities are still disabled at this time.
We're continuing to investigate latency affecting successful sales and purchases on the gold auction house. Please note that while these issues may cause a temporary delay in having purchased items appear in your Completed tab, your items have not been lost. If you do not see your purchased items immediately, please check back later.
We're aware of issues affecting our authentication servers which may cause players to experience failed or slowed logins (e.g. getting stuck at "Retrieving Character List"). We're currently investigating the cause of these issues and have brought all Diablo III game servers offline for maintenance. We will provide updates as they become available.
Thank you so much for your reports!