Dying from suffocation when entering to or from a nether portal

You will enter a nether portal to the nether or out the nether, your screen will not load to the dimension but you will hear a damage sound, then you will die of suffocation without knowing where you are.

In our world I have all my stuffs on me almost fully decked out, and I also have my treasure box with me. I entered the nether safely, but going out of it, I died of suffocation. Will not enjoy playing in a world if this is not fixed. THIS MUST BE FIXED, IT IS SOOO FRUSTRATING!!! 

 

Second time this happened...