Black or Frozen screen when calling

Galaxy S:

When i make a call, the screen truns black. I can't hang up etc.
Also when someone's calling me i can't press any button for like 30 a 40 sec, then sometimes i can hang up.

Tried everything, Flashed 6 different firmware versions using ODIN, Even brought back to the store, They flashed it to, no effect.

BUT!! When i plug in my headphones the screen does not go black and don't freeze, It functions normally then. THAT is Strange!!?? 

Any body an idea??

Also another problem:

When the screen is locked, and i press the home button, it takes about 10-15 seconds to show the unlock screen. When i press the home button the screen just stays black for 10 seconds until i can unlock it with a swipe.

Thnx, it vibrates all the time, and went green immediatly first time, but when i did it again it just vibrates and stays white if i come near the sensor

Also it states, ''need for calibration 0''

I don't use any kind of casing, still did not manage to fix this problem, i'm hoping for a custom Rom where i can choose to completely shut down the sensor.