As I'm experiencing this bug too, on an xps m1330n, i did a little bit of research.
I tried to follow the walkthrough in post #7 but that failed, as I couldn't change the mic input.
I then reverted alsa-utils and alsa base to the first karmic version (1.0.18 for both of them) and, while the mic was not functioning straight away, I followed the forementioned walkthrough which resulted in a **functioning** mic.
It therefore seems an alsa related bug.
I will try to narrow down the problem tonight.
As I'm experiencing this bug too, on an xps m1330n, i did a little bit of research.
I tried to follow the walkthrough in post #7 but that failed, as I couldn't change the mic input.
I then reverted alsa-utils and alsa base to the first karmic version (1.0.18 for both of them) and, while the mic was not functioning straight away, I followed the forementioned walkthrough which resulted in a **functioning** mic.
It therefore seems an alsa related bug.
I will try to narrow down the problem tonight.
ps: i downloaded alsa-base and alsa-utils from https:/ /edge.launchpad .net/ubuntu/ karmic/ amd64/alsa- base/ and