The server occasionally goes down. When it does, nobody can play which is a bummer, right =) This happened this week sometime (though I think it was on Friday) but I was away all week and didn't like leaving it alone for so long. Normally I check it every day and make sure it's running. Of course this is less than optimal!
At first I thought this was a bug in the server program but last night I realized it is inevitable and something to do with the way the database is organized. Anyhow, the bottom line is that I'm testing some new server code that should improve reliability a lot.