Greetings. I have a very similar problem. There is sound in Windows ME with the WDM driver, but if you install the VXD driver, the sound disappears. And in Windows 98 there is no sound at all, both with the VxD and with the WDM driver. At the same time, there is sound in the system itself in all cases. Sound is also available in older versions of Firefox (<14 and some early nightly alpha builds of 14). Starting from version 15, the sound is no longer available in all that I managed to try at the moment. I don’t know what to do with this problem, so far I see the option of installing a separate sound card with WDM drivers, especially for browsers, or looking for some purely software sound card emulator based on WDM drivers. And the fact that you have CMI8738 sound under Windows 98 SE, with installed WDM drivers is a very good sign (In terms of WinME is not required in this case). Because I have sound on SoundBlaster16 only in WinME and only with WDM drivers. This may mean that the WDM driver for CMI8738 has some key files that give sound to Windows 98 SE (not only in WinME, as in my case).