Try connecting the DS18B20's 5V and GND both to GND and just use the pullup on the signal pin to 5V for power.Don't ask me why they sometimes don't work if you connect the 5V to 5V -- I don't know.
Programs run fine, but no response from DS18B20.
No luck with parasitic setup, or standard 5v setup with 3.3K pull-up. Maybe the images tell something.
It seems unlikely to me, but I suppose it could be a DOA sensor?