Something wiped out my 5.1 channel output

It happened once, and now happened again...
It has something to do with Winamp, I think.
Even DivX encoded videos, 'till yesterday, played using my central and subwoofer channel in a analogic 5.1 channel setup (using InterVideo's WinDVD AC3 decoder).
Now, for some reason, it just stopped working.
All Windows configurations are correct, DirectSound, and the InterVideo configuration... all correct.
Something messed up these configurations, then I fixed everything up, but now DivX Videos won't work with my central and subwoofer channel's... anyone have a clue why?