please help, my burner is burning a blank space 1/4 of the way through the disk

my burner is burning a blank space 1/4 of the way through the disk, I have used anydvd, clonedvd, dvdfab,dvdshrink, dvd decripter, and it does it with all movies. I have been burning for 3 years and never ran into this problem, the movie burns fine, no errors,but you can only watch 30 mins of the mivie and it freezes. When you look at the disk there is a dark grey line burned in the disk, and it is in the same place on all of my disks now, it started about 2 weeks ago, has anyone ran into this problem, my burner is a lacie D2