The whole pool is down right now. DDoS attack. Read this https://defuse.ca/bitcoin-pool-ddos.htm if you want to understand why this would be worse if Slush's Pool was a much larger operation. I'm mining solo until the pool comes back.

Very interesting. I feel like I would have figured this out on my own if I was a little bit more intelligent.

Stratum seems to be down as well now.