I have same problem.
Toshiba L300 Vista
"No audio output device" Near the speaker sign with red cross.
I try reinstall driver. Removed the yellow labelled audio device, Restart my computer, but after it the computer do not find audio device. :(
I try manualy, add device, realtek High definition Audio, but the answer "can not starting Code 10" ) :(
I try to set factory default the all laptop with Toshiba HDD recovery, but after full erase the laptop can not find audio device :(
Any Idea? my last chance to upgrade to win 7 but I do not belive in it....