Getting horrible feedback upon the start of recording when using TH3

Hiya,
 
I'm revisiting a project, haven't touched it in weeks.  When I try to lay down a guitar track, I get horrible feedback through my speakers.  Stepping back, though, I can't seem to get any sound out of TH3.  Existing tracks (audio and MIDI) play back fine, but it seems the signal stops at my audio interface (Tascam US122 MkII).  The meter is showing a signal, but nothing in Splat shows an incoming signal.  I've gone through the signal chain and nothing is different - at least that I can tell - from the last time I opened the project.  I'm thinking this ear-splitting feedback has something to do with it.  Anyone ever run into this or have an idea of what's behind it?

Alrighty, then.  Just rebooted, everything is fine.  Nothing to see here, just keep moving.