The welcome [Name], and Charcater section both show "An error has occured: Log Out".
Multiple Browsers (Chrome, Firefox, IE9). Cookies and cache cleared.
DNS set to manually point at my ISPs DNS server and then Googles public one (changed on router/modem).
Router/modem reset.
PC restarted.
A bit for research indicates this also happens to users of the EU forums who have a US game account attached to their main account when the US goes down for maintenance. I have a SEA licence for SC2.