Tim,
Those are sent every time the connection to a client device fails, as the WiThrottle Server retries to connect several times.
If you're seeing these often, I suggest finding a less-crowded wifi channel, and/or installing a better wifi access point. You didn't mention what you're using, so I can't be more specific.
EngineDriver (and I presume WiThrottle) resyncs on reconnection, so you may not even notice it was gone.
--SteveT
