No system sounds or volume icon in XP Pro

I am running XP Pro, and at some point in the past month
or so my OS lost the ability to play system sounds and no
longer displays the speaker icon in the taskbar tray. I
can play sound in third party apps such as Winamp,
PowerDVD,Windows Media Player, etc...but there are no
windows sounds. There are no conflics in the device
manager, and no new hardware has been added. In the
control panel the "place volume icon in the taskbar"
checkbox is checked and my SoundMAX digital audio is
selected as the default playback device. Nothing is muted,
volume is up in the control panel and on my speakers
(naturally, because I get plenty of sound when
playing .wav files through winamp). Under the sounds tab,
the play button is greyed out, preventing me from testing
the windows sounds, but if I open those same sound files
in winamp they play just fine! I also noticed that I get
no sounds when surfing the net. Any help with this would
be much appreciated, as I am becoming increasingly
frustrated.

Thanks!