Hi, I am a new comer here. I am glad that there are so many warm-hearted experts to help people here. I have a problem about my audio driver here. I bought a Dell Inspiron 6400 one month ago. I reinstall the OS (XP pro.) and all the drivers by myself. It worked perfectly. However, after i install the software for my new cellphone, (SONY-Ericsson 810i) on my laptop to transfer the audio, video and the pics, the sound card drive disappeared. So I reinstalled the driver (for this laptop, the audio driver is :SIGMATEL STAC 92XX C-Major HD Audio). The audio is back. But after I restart my computer, the audio is gone again. To solve the problem, I uninstalled that software for cellphone and reinstalled the driver again. This time, if I open some sort of audio player such as Windows Media player, the audio works fine. But if I close the audio player or shunt down the computer, the driver is gone again. Now the situation is if I need the audio works properly, I have to install the driver at every time I re-open the audio player or restart my computer. I guess somehow that cell-phone software screw my audio driver system. Does anybody know how to solve this problem? Thanks!