I just spent ninety minutes trying to understand why my MySQL server wouldn't allow queries (seemingly) from another system. I run ISBN.nu from two Linux rack-mounted systems at my co-location host, digital forest. An alert from my monitoring system said the system was down.Sure enough, I couldn't run queries from the Web server to the MySQL server. I tried many tricks that have worked in the past -- flushing the host count for rejecting hosts that have too many errors, restarting both systems, etc., etc. I read dozens and dozens of posts, trying to find something comparable. And I finally did. The thread_stack setting of 128K is inadequate when you run up against certain domain name resolution queries. Of all things. The solution: put the remote host's name in the /etc/hosts file to avoid a get_by_host request. Yes, it's obscure, but I could never have figured this out without the collective, archived wisdom of smarter (or more desperate) people.