Sudden annoying beep from Red button

[procrastinator!]

hi Guys,
Anyone know anything about this? (I've spent a while searching, and can't find a thread on it. . ."

Suddenly, my phone has started emitting an annoying and rather loud "beep" (more of a "boop" really) whenever I press the red "hang up button"
I 've had the phone for months and never heard this tone before. I had recently performed a hard reset to clean it up and fix an unrelated problem. I had recently reinstalled a few pieces of software that I had run before, without encountering the tone. (I think is was the large start menu, and the HTC dialer and comm manager skins)

I found a brief discussion of this on another site, but can no longer seem to find it. Not quite sure what my search terms were. It suggested moving "Windows/Mid2wave_079-4098" to the memory card. I have done this, but it always "comes back" after I soft reset. Besides, when i play this file (it's a .wav file) it's a different sound.

I'm running the most recent Sprint ROM.

Thoughts?

Thanks all!