Optimizing ZWave Network

As part of a problem-solving exercise, caused by one of my power switches suddenly not being seen by Indigo, I ran a ZWave Network optimization....the logs tells me it fails to ping ANY of my ZWave devices, even though they seem to be chatting quite happily in every other way to Indigo. Is this normal? A snippet from the log:

Z-Wave Optimizing - started network optimization for nodes: 7, 8, 9, 10
Z-Wave Optimizing - starting "007 - TRV Trevs Office"
Z-Wave Debug SENT sendPingZwaveCommand: 01 09 00 13 07 02 00 00 25 F3 36
Z-Wave Debug RCVD sendPingZwaveCommand: 01 07 00 13 F3 01 01 D2 CA (node NAK)
Z-Wave Optimizing - ping failed (could be asleep)
Z-Wave Optimizing - skipped "007 - TRV Trevs Office" (unreachable)
Z-Wave Optimizing - starting "008 - TRV Lounge"
Z-Wave Debug SENT sendPingZwaveCommand: 01 09 00 13 08 02 00 00 25 F4 3E
Z-Wave Debug RCVD sendPingZwaveCommand: 01 07 00 13 F4 01 01 A8 B7 (node NAK)
Z-Wave Optimizing - ping failed (could be asleep)

[matt (support)]

Presuming those are not battery operated modules (which will be asleep and Indigo won't be able to immediately reach to optimize), then that is strange. Try unplugging the Z-Stick from the Mac to see if that helps. Also try moving one of the modules (if it is a plugin type) to be within a few feet of the Z-Stick. If none of that helps then I think the Z-Stick has gotten into a bad state. You could try excluding a module and re-including (then resyncing) to see if that helps.