I use headphones with a built-in microphone. They are plugged into the correct ports on the back of the computer (I've checked, double-checked, triple-checked). I have tested the hardware in the Sound Playback section of Control Panel>Sounds and Audio Devices>Voice>Voice Playback and it works just fine.
However, Skype does not detect input from my microphone when I make a test call. Their directions say, "In the Sound Recording, click the Volume button and check the following (in Recording Control window):
Microphone has to be checked in."
Windows will not let me check the box for Microphone.
Skype's directions further read: "All other options have to be checked off."
Well, in my Recording Control window, Stereo Mix is checked, and Windows will not let me uncheck it.
I've tried everything I can think of, and yes, I have searched the archives here for a similar problem, and didn't find a solution. I've also read extensively in the Windows XP knowledge base at Microsoft.com, and haven't found any clues.
The gurus here do such a great job solving other computer mysteries. Any ideas on this one?