Recording is becoming messed up

I record directly from my speakers in Audacity (specifically, Stereo Mix (Realtek High Defini) and in doing so, I have created perfectly accurate recordings… until a day or two ago (4/23/2013 at the earliest).

At that time, all my recordings began to experience an odd problem. It’s like the audio gains an echo and just bellows out.
And the same thing happens when I use the Primary Sound Capture Driver, albeit a bit differently (either the issue reduces or increases).

I’m using Windows Vista with Audacity 2.0.3.

I’m fairly sure it isn’t space causing it because it happened once with over an hour of space left.

An additional fact: the same thing happened with my screen capture software (ZD Soft Screen Recorder).

Ensure that Skype or other voip software is not running (not even in the background).
Check your sound system settings in the Windows Sound Control Panel.
In particular, check that Windows sounds enhancements are disabled:

Okay, it worked. Thank you very much.

But why did it happen in the first place? Did Audacity somehow change those settings, or were they always like that?

And as it turns out, everything is now sounding like it used to, as when this happened, everything actually had a very subtle change to it.

Skype is known to change the sound system settings (without asking).
Another possibility is that there may have been a Windows update that changed the sound card drivers and/or settings.

Skype always changes system sound settings. Sometimes it forgets to put them back. If it’s running in the background it usually keeps its settings. Koz

Thank you very much for telling me this. I can rest a little bit easier now.