Comment 2 for bug 366690

Thank you for taking the time to report this bug and helping to make Ubuntu better. However, according to this report, you are not using the most recent Ubuntu release. If you are not currently running the latest version of Ubuntu (9.10), please try the 9.10 live cd and let us know if you are still having this issue.
If you still experience this issue when using Ubuntu 9.10 live cd, please install Ubuntu 9.10 & then also install "linux-backports-modules-alsa-karmic" (then reboot) because that package enables audio on quite a few HP laptop models and contains much improved support for microphone auto-switching.

If this does not resolve your issue, please provide the model of laptop (e.g dv9000, 6930P, etc.) for us to be able to further diagnose your issue.
Thanks in advance.