First, have you downloaded and installed the WMP 9 codecs? If not, here's a link:
Codec Installation Packages
Next, Is it true that you're problem is only occuring when you want to play "Windows sounds" such as those that happen a "events" on the computer?? (Arrival of e-mail, exiting a programs, etc.) ? If so, have you tried changing/adding sounds? Maybe your sounds theme is changed.
Open the Control Panel, double click on the "Sounds" or "Sounds and Multimedia" icon, then click on the "Sounds" tab. In the "Events" section, highlight a particular event and make sure there is a sound for it and test the sound.
Hope this helps.
I run win98se and have used Win Media Player for several years. Recently I have been unable to get audio on website and email attachments nor do I get audio on various pc alerts (email, reboot, etc) I do get audio using disks. I recently downloaded Win Media Player 9 but still get no audio. I always suspect that I have made changes unintentionally and often can't retrace my steps! Windows Support (Audio Troubleshooter offer no useful help) Any suggestions? Many thanks, Carr