Can't really pinpoint when it happens but it happens only sometimes upon: -opening reaper (empty) and loading the plugin -loading a TS808 -loading a cab IR I can't find any order to it, it just happens. Also, the BassDrive also will crash it if I open it with ToneLib. This is all GREAT software. Glad to have it in my plugins list. The ToneLib for Zoom is also amazing! I just downloaded it and have been super happy editing for my Zoom G1xon with this. It will make life much simpler!