I keep missing calls !!!

Here is the situation...

My SE W960i rings and I try to answer the call.

The bottom of the screen displays Answer? and and a virtual [Yes] button is displayed bottom left.

I am supposed to press the virtual [Yes] button but it's not a real button and simply out of habit from my old phone I often press the nearest key on the key pad.

Unfortunately the nearest key on the key pad is the [back] key which causes the caller to be cut off.

Oops...