We apologize but one of our database tables “crashed” and needed urgent repair. The issue was causing several of our main site features to fail (search, downloading, and registration). We originally hoped we could do the repairs overnight and just limp along until then, but it soon became clear we had to do this ASAP. This sort of thing can happen periodically with MySQL, it’s not a big deal, just takes a little while to rebuild the index. We use replication and backups, so no data was lost. We just brought the site back up after about 2 hours of down time.
Again, very sorry for the inconvenience!