I've (again) fouled something up while tidying-up my system. At the moment, my speakers will happily play a music CD, but whever a standard 'computer sound' (Windows sounds, sounds accompanying downloaded videos, etc) is called for, the speakers will only emit a varying series of popping noises. These will play overtop of the music (as normal Windows sounds would), and answer to volume control. I have tried reinstalling Windows, reinstalling soundcard driver, and a variety of other similar attempts - all for nought. Any suggestions?