Me neither, sorry. I haven't heard of Windows choking on disabling a peripheral device since Windows 98 days. But 3 soundcards can be a handful I guess. A quick search on Google didn't turn up anything similar or useful yet and I'm seriously stumped.
Are you sure all 3 devices won't do any sound? Not even the 404?
Edit: Ah, cool. Then you know what you probably have to do tomorrow, try to get the Soundblaster working w/o the onboard sound (unless the initial DPC issue fixed itself somehow).