The first thing to do when SoundTaxi is not working right is to re-install it. The same goes for the KKBox as well. If there was a problem with the files and registry items, it should be cleared and fixed through re-installation.
This could also be a compatibility problem. If one application was updated, then the other one needs updating as well in order to work properly.
Contact SoundTaxi support: http://www.soundtaxi.info/support_area_form.php