As far as I know "black corrector" makes grey colors black, therefore there is more black on the screen and you get the impression of an overall blacker image. Down side: You're killing details (two dots before black correction: black and grey. Those same dots afterwards: black and... black). That's why I'm NOT enabling black corrector.
But that's only a pretext for me posting the next part of my neverending Sony TV story...
As you know my TV got a free dis- and assembling service last week. I had not that much time afterwards, but this weekend and today I finally found some hours to spend with my TV. So I'm sitting on my couch today, watching a Battlestar Galactica episode on Blu-Ray. But wait... there's something... not quite right... in the upper right corner. Can it be... impossible?!?!
Well... I turned out the lights. And then... it was there. In all its glory. Same problem as Joker's. Twin brother of the one in the upper right corner in this picture
It definitely HADN'T been there BEFORE the (attempted) repair. So... why the hell now? Then I tried this: Went to the upper right corner with a screw driver and loosened the two screws located there. The second one being VERY hard to turn. And voila - flashlight unvisible under normal light. Not the same as before (you can still see it when watching in a dark room, but I'm almost never doing this...).
Next time the support guys are here I'll tell them NOT to tighten the screws...