Major Description
It's very unclear what the issue here is, and it's likely related to an underlying system issue, but it would be good if we could get a handle on our response to this and perhaps make it better going forward.
Log file attached, comment from Alk: Something is wrong with stats in this particular case. ep-engine and/or memcached are apparently sending empty values of stats. I suggest you to file bug for that. Information on what they did would be helpful to reproduce. I haven't seen anything like that. Could be win-specific issue.