just guessing, but maybe ur 851 is less tolerant of that media. I don't readily see why, but just in case u don't have too big of a stockpile left, try another type. I was gonna suggest maybe its burning in DAO96 mode, since that caused problems for me in the past, but dao96 mode wouldn't give u errors like that just because of the mode.
another test is to flash it back to 451, burn and check what the scans are like for reference.
keep us posted.