I have a new Nokia 6630 that has started randomly going into "headset" mode. That is, I get no sound, no one can hear me (without the headset), and when I end the call, "Headset" is shown on the display, just like there is a headset plugged in, but there isn't. Any ideas what to look for? Or, is this a known problem with these phones? If it is known, what's the fix?

thanks. Pallav