[R-390] What's going on here?

[Barry]

Your radio was jealous of the attention you were giving to your computer.

Barry - N4BUQ

> I have been sitting here answering email with my R-390a on but turned down.
> Suddenly the audio comes up like I turned up the volume control. Wiggling
> the local gain back and forth doesn't fix it (and is not scratchy
> sounding). Finally I flipped the function switch back and forth to CAL a
> few times and it went back to normal. What the heck?
> Tony