What speed did you burn this new batch of discs at (as some drives will overspeed them to 12x)?
Have you tried a different batch of TYs/another brand of discs to see if they TRT with the same results?
Just on the off-chance, is the DMA for your 115D set correctly (i.e. UDMA Mode 4, not PIO Mode) in Device Manager?
BTW, the yellow line is the drive's RPMs and should be a straight line across the graph...as you say, the green line should be a nice smooth upward curve, though.