You may have noticed that Valhalla was down yesterday and that now, data seems outdated. Unfortunately our server died and we had to relocate. And unfortunately due to poor sysadmin work, we had to restore from an old backup for now. We'll continue trying to recover the lost data, but in the meantime many users may have lost their accounts. Feel free to re-register (since data recovery may not be possible anyway). We're sorry for the inconvenience.
Let me know if you notice anything broken on the site. There are a few things which I expect are broken (like the SQL challenges).