Hello jrball,
Does Task Manager show any process using ~100% of the CPU time?
To confirm, do you mean that the problem occurred when St. Anne's was left loaded with audio/MIDI active overnight, and that it was working when you left it yesterday, but wasn't responding today, without you having touched anything at all in Hauptwerk today? Had the computer gone to sleep during that period? (Computers going to sleep sometimes cause audio, MIDI or USB device connections to be lost, and thus indirectly freeze applications that were using them.)