I have been able in the past to record whatever sound is playing on my PC, simply by clicking the Record button in Vegas, opening a new track and monitoring the sound level. After finishing, I would Normalize the cut and play it back, no problem.

I have used this feature to listen to web radio stations and record to make CD's to play back later. I tried to do this again this morning and was unable to get anything when a recording was made. I checked my sound card settings, turned up volume levels, tried recording a short clip (sound heard clearly on speakers at all times), made sure nothing was muted. I noticed the track level meter had only a background noise level static being shown at all times, and when Normalized and played back, there was no audio except for a high-pitched squealing (but it wasn't feedback, I don't have a system microphone).

I have recorded just like this just the other day, fine. I have not changed my hardware or any settings. What in the world has happened to my audio inputs!?!?*&%^#@