Incorrect identification
I solved my problem with exactly the same symptoms the other day. Seems that the system made an incorrect identification of my on board sound device :4-thatsba .
I went through various methods, update driver, manufacturer homepage etc. Then I simply tried my old win 98SE which I had on an older harddrive and with which the sound device was working.
Win XP identified the C-MEDIA AC97 Audio Device, the manufaturer hompage indicated it should be a sis7018 and finally the old win98 said sis7012. The last one ti was :smooch: .
So try to make an 100% certain identification of your sound device, download the correct driver and update manually :sayyes: .