David E. Ross wrote:
Windows 7 Ultimate SP1 x64
Skype 8.34.0.78
Logitech HD Webcam C510 model #V-U0016
Cyber Acoustics CVL-1124R microphone

I have two problems.

[Forced updating issue already addressed by John.]

Second, I tried a video Skype session this afternoon with my daughter.
She could see me, and I could see her. I could hear her, but she could
not hear me. I verified that the microphone in the webcam and the
separate Cyber Acoustics microphone were both enabled, but she could not
hear me. I was able to record sound locally on my PC from both
microphones, so I suspect there is a problem with my Skyp setup.

Did you (and she) try the built-in 'Echo / Sound Test Service'? That
should reveal which side has which problem.

Same for Settings - Audio & Video. That should reveal if the Camera,
Microphone and Speakers work on each end.