If so, maybe Jeff's tip will work:
user.scheduler.prefs.runThreads = true; scheduler.monitorThreads ();

Or could it be related to my fresh install of liveTopics?

The key to a successful fix: I see in my Radio Events Log numerous instances of
Upstream   Can't upstream because "The file "liveTopicsTOC.gif" wasn't found."

So I retrieved missing image from Matt's site--
http://radio.weblogs.com/0107808http://maikimo.net/radio/images/liveTopicsTOC.gif

and put into my Radio installation's www/images/ directory.

Works!
7:17:21 PM |  See also radio livetopics upstreaming