HTC Evo 3D.
So, if I have this straight - something about the angle of the phone to your face (shape, etc) is such that it doesn't show you are close and it switches back on then?
In such a case, I think that you need to only jockey the phone so that the proximity sensor stays close enough. On an HTC, that's usually at the top, by the ear speaker. If you hold that part closer, the bottom flares out unacceptably?
Is that the deal??