Quote Originally Posted by jdc2000 View Post
According to the specs I found, assuming that they are correct, that monitor does have built-in speakers. If is possible that, for some reason, the monitor thought it needed to display an audio control of some sort. You might try using the setup button(s) on the monitor itself to dig through the available monitor-controlled settings to see if you can find anything that looks like the control you saw on the screen.
I am thinking the same thing. May also be that the volume button on the monitor is stuck somehow!