Sorry folks, major problems with DTT in Auckland and South Island starting around 5:30 tonight. It seems different receivers reacted differently to the problem, some were fine, some lost audio and some lost pictures as well. Exact cause is unknown at this stage but everything should be back up now. Anyone still having problems should first reboot their receiver, then try rescanning the channels.
Device behaviour like this, albeit infrequent, does not bode well for the future. Older people, or non tech people could be left without watchable channel(s), thinking their 'telly' has died, until they can get assistance from someone who can do a re-scan for them.
Would be interesting to know why such a problem can occur and affect some devices and not others.