Dear all,
I think this question have been surfaced many times, but after searching for answers sometime, I just have to post again. 
So bear with me.
Machine: Lenovo ThinkPad Edge E220s
Purchase date: October 2011
Description: Laptop
Audio: Internal Microphone (Conexant 20671 SmartAudio HD)
Speaker: Speakers (Conexant 20671 SmartAudio HD)
- In English, that is the internal speaker.
OS: Windows 7 Home Premier 64 bit
Skype: 5.5.0.124
- In English, that is the most up to dated version
When I try to call the Echo / Sound Test, after hearing the lady says hello, I see a message box comes up:
- Microphone tab has a red exclamation mark.
- Speaker tab has a read exclamation mark.
In each tab, there is "Can't access your sound card" message. Sometime I see another small box at the bottom right saying "No microphone detected."
What I have done
1) Tools -> Options -> General -> Audio settings
For Microphone and Speakers, I have uncheck the auto adjust settings.
Restart Skype. Do the "Echo / sound test" and same thing. No detection.
2) Edit AppData\Skype\shared.xml
[ Edit: It seems like the editor here does not like the percent sign before and after the AppData.]
a) I make sure the line AGC XML tag has a value of zero (0).
b) I make sure the MicVolume tag is just 100.
Restart Skype. Same thing. Not working.
3) Test out speaker and microphone in the Skype welcome screen.
The speaker always works.
The test on microphone works sometime and does not work sometime.
Help please! I have less than 24 hours to make a very important call over Skype! 
