[JesusRocks]

Right, I have used Audacity to record 8 out of the 10 songs I have deemed good enough to record. On the 8 tracks, the sound quality has been fine, my microphone has picked the sound I want, at good quality.

However, recently while coming to record the ninth song, I'll record the track and, on playback, the audio is absolutely fine for the first 3 or 4 seconds, but afterwards I get this sudden drop in quality, where the audio goes quieter and it sounds like I'm recording underwater.

The best I can describe it is a sudden quietening and the addition of a metallic reverb that overall makes the audio quality horribly tinny.

It's definitely not the microphone, because this happens with whatever mic I use for it.
It's definitely not the connection in the audio jack, because it happens with the integrated microphones on my laptop
And it doesn't seem like it's anything to do with Audacity because the same thing happens in Windows Sound Recorder.

Now, I know my laptop is on its way out, and so I'm wondering if this is a driver issue, or that the sound card is on the blink.
But I know nothing about that, so forum, I would like your help.

What is wrong with it? and how do I fix it?