MinionPro-Regular.otf
And what is the full path to this file?
I speculate that it is under truetype/ rather than under opentype/.
There was a duplicated+incorrect definition in texmf.cnf.
Now we have just the one:
OPENTYPEFONTS = .;$TEXMF/fonts/{opentype,truetype}//;$OSFONTDIR//
Hope that solves it.
k