vista sound stops working in firefox, winamp, still works in ie,wmplayer

I'm flommoxed. Without installing or changing anything in particular,
my sound stopped working in some non-windows apps, and not in others.
I'm running vista ultimate as I have been for some time. Winamp will
immediately move quickly down its playlist without displaying any
error; firefox won't error on youtube videos either, displaying the
video fine--just no sound. ie and wmplayer operate perfectly. media
center and video games operate fine too.

I'm having real trouble with any google-fu restricting to when only
some apps are having trouble with sound, as opposed to no sound at
all. Nor do I have any prime candidates for debugging, not doing or
changing anything out of the ordinary; certainly not any sound
configuration changes. The closest thing to this happening before is
occasionally the sound wouldn't work when i'd log in locally after
having been remoted in at work: it usually yielded a directsound error
and corrected itself, or a reset took care of it. that's not the case
now.

any help would be greatly appreciated.