In
this thread it was mentioned that some town criers are also keeping their traps shut. Could be related.
OH! OH! OH!
Not sure if this is it, but when the Inu the Crone quest and Moonglow blackrock even were going on, I could double click on event NPC's and Town Criers, and a special menu would pop up. The menu had the title of "Crazy Lady Control Panel." With this panel, I could review all messages currently active, load my own, batch load new messages and delete messages.
At first, I thought it was part of the event, and fiddled with it to see what the NPC was trying to tell me. A friend was with me and I couldn't hear or interact with her while the control panel was up. She ICQ'd me and I realized something was going on. The messages I put in started playing when I talked to the NPC. My friend didn't believe me until she told me to put in the message "Free lap dances in Lord British's Castle!" I did, and the NPC spewed the message! I immediately deleted it...
I couldn't resist the doing something really bad, so I PM'd Jeremy and asked her to fix my character. It was just too tempting!
What I am thinking is, some NPC/Town Crier messages got deleted, NOT that they are silent.