Can't turn sound off

[Tomtanium]

Never had this problem before, but I recently upgraded from Win98 to XP. I also changed from a micro on board modem to a PCI card modem, in particular a Connexant. Since installing and updating the driver from Windoze, the modem won't turn off the sound from the PC internal speaker, not stereo ones. I have of course done the obvious things like turned the slider in MODEM PROPERTIES to the off position and also tried adding the string "M0" capital M and number zero, in the advanced, and in My network connections disabled modem speakers from Modem config.

Any ideas anyone?

Thanks

Tom