Soundcard and Harddisk usually have separate IRQs. Well, nowadays Soundcards not always, IRQ-sharing is everywhere. <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />
From this assumption on I'd say that there is a slight conflict between the operating system's work with both IRQs at nearly the same time (loading -> access to harddisk , music -> soundcard). Could be Directx also.
