The blue hearts when you freeze to death if you are in powdered snow don't display if you use the Programmer Art texture Pack. It looks like you have no hearts at all, which means that you can't see if you are dying or not.

I made a screenshot which i'll put here, too. (Even without the leather boots which are in the screenshot, you can't see the hearts.)

-TheWitherSkull   (aka T_W_S)