Yellow circle we heard a loud pop, now we have a hazy yellow circle in the center of the picture, I replaced the bulb.

There are a couple of things that this could be caused from.. Its hard to say without actually looking at the set, but they are as follows.

The lamp is what you heard pop, they are under extreem pressure when on, and when they get to the end of there life, they will expolde if not changed in time.

The circle can be caused by 3 things.

1 : when the lamp exploded, it knocked the internal mirrors and lenses and or burned them due to high heat and brightness of the explosion.

2 : The polarizing filters that are infront of the lcd could have also gotton burned.

3 : The lcds could have also been burned.

If the haze happened right after the pop, I would expect that you bumped one of the lense or mirrors in the optics out of whack or even cracked the glass. If the haze has been present prior to the pop, then your lcds or filters are shot.