My shiny new 7720 arrived last week and all worked well.

But yesterday, I started getting feedback echo through my speakers.

For example, even at a low speaker setting, the speakers are emitting the sound of my keystrokes - with an audible echo!.

If I increase the speaker volume to more than about 10% then the speakers quckly start emitting a loud high pitched tone.

Anybody know what the problem is and how to fix it?