No sound from any application, but sound from WM11 music player.

Hi, this problem just began for me last night, I didn't notice it at first
until I opened up Internet explorer and realized there was no sound from
anything. Not from streaming video, clicking buttons, anything. Then I
realized I had no sound from my desktop, no sound from error messages, or
clicking things. I did though have sound from playing music in Media Player
11.

I use Logitech USB headphones, and Dell Speakers with Creative X-Fi Xtreme
Audio sound card. I have checked for updates, none. Device manager says their
working fine. Nothing is muted and the volume level is fine because I can get
sound from music and video playing in WMP.

Any suggestions?