A bit of looking around didn't help much, but someone mentioned a permissions issue. Here's the log entry:
Sep 12 18:13:56: vmx| CnxAcceptConnection: Could not receive fd on 187: invalid control message
Sep 12 18:13:56: vmx| Failed to get IPC connection
Going out to the directory of the VM, and executing a "chown root:root -R ." did the job. Restarting the VM after that brought it up nice and happy. So the question remains as to what caused this to occur.