Backlight turns Off When I make a phone call

[DLCPhoto]

Lately, whenever I make a phone call, the display either turns completely off as it connects, and never comes back on, or it goes black for a second or two and then comes back on.

If it goes black and doesn't come back on, the proximity sensor doesn't seem to do anything, and I have to hit the on/off button on top to turn the display back on.

If it goes black for a second or two and does come back on, the proximity sensor still doesn't do anything. I'll hold it up to my ear and it doesn't turn off.

I'm not aware of any regularly accessible settings, so assume there is something funky in the registry settings for this behavior. Can somebody point me to the appropriate registry keys, and what their values should be when the proximity sensor is functioning properly?

I'm using Verizon TP2, Stock 6.1 ROM.

Thanks!