Pulsing sound being inserted into recording (SOLVED)

Win XP. Audacity 2.0, Firefox browser, DSL connection.

I have clicked on something and the following problem has started:

I launch Audacity and click on the orange “record” button and I can hear a pulsing tone being inserted into the recording. When I try to record sound from a Youtube video, the sound that I hear sounds like that the singer is in an echo chamber. I caused this problem while using the old version of Audacity and I installed version 2.0 (exe installer) hoping that this would go away, but no luck. I don’t know what I did to cause this problem and I don’t know how to fix it. Hope you can help. I don’t know much about Audacity, but I have had very good luck with it in the past when trying to record sound from You tube or any other audio on the internet.

JAS

Look in the Transport menu and ensure that “Software Playthrough” is not enabled.

That was the problem. I unchecked it and everything sounds normal now and the recording sounds great.

Thanks for your help with this problem.

JAS