That's the failover system in action! Pools have been going on and off line all the time for the past week. Right now, for example, both slush and deepbit are down. For now, I have decreased the leniency for pool errors to decrease downtime durations (it is still more profitable though to mine in a pool with high connection errors and high expected utility, rather than one with no errors and low utility), but will continue to tweak the criteria and will implement round-robin fail-overs for zero downtime.