Did you ever come up with a solution ? i am having the same problem.
I guess it's time to bump this, since we just had a massive number of agents do this on 8-5-2012 early in the AM, and then succeed since!
I have opened a ticket with K support asking for a followup and countermeasure.
Wow, still seeing this - it'll happen on one "cycle" where I get the failure, then the next time it tries it succeeds. It really doesn't seem like it's anything on the agent/endpoint, it seems like a wacky database issue. Their response was "Upgrade to KES 2.2" which I did, and the issue wasn't back *immediately* so that ticket got closed. I guess I'll be opening a new one though, or just living with the issue until we make the big jump up to K6.3 and KES 2.3 as well. Yay fun