Windows 7 stopped acknowledging the onboard speakers on my Dell notebook yesterday. The only output options I had were via the HDMI port and the headphone jack. Everything looked normal in device manager (no missing drivers) and no new software was installed to my knowledge. I ended up fixing the issue by re-installing the audio drivers from the DVD that came with the computer. Since Windows 7 was not the OS that came with the computer when I got it I had to choose Vista as my OS, but everything installed normally and the issue was resolved.