I too have same issue with same media on my Lite-ON iHAS120-4. After I disabled all four "nice" features of Lite-ON drive and set media speed to 6x, I was able to burn those DLs without problem, write completed, verify OK. My Sony DL also has similar issue, speed down to 0.1 in random position. I don't know whether it is caused by Lite-ON's Smart-BURN, Hyper Threading or due to the mis-communication between ImgBurn and Lite-ON drives. My Lite-ON has 7L0E firmware. ImgBurn used to recognize Smart-BURN. But for unknown reason, it didn't recognize this unit as a Lite-ON.