RE: cannot get sound on Toshiba laptop
I know for sure there were some problems of this kind that got solved
upgrading to 2.4.19(pre3 or higher)
On 2.4.18 sound seemed to work, no error message, but no actual sound, or
_very_ low volume)
>From 2.4.19 on sound was functionnal
If my memory is good fixes I am talking about were about ac97_codec support
on some audio chips, which you seem to use.
Though I dont know specially about Yamaha YMF754B-R ; but I would try
upgrading to 2.4.19 if I were you.