What does Photolab 6 "loading error in block load" mean

You are incorrect. PhotoLab claims to support DNG when it doesn’t properly support DNG. PhotoLab only has parial support for DNG as discussed at length in this thread: see here .
It is not a corrupt file if lightroom can read it. [stephenie ] (Profile - Stephanie - DxO Forums) you might want to join the other thread referenced.