Just to contribute a little bit....power calibration (if you don't already know)
1. Cheap media, you state you typically use TY's so shouldn't be a problem.
2. Bad power from PSU or bad PSU, check connections and cables and maybe try different ones.
3. Burner has one foot in grave, replace drive.
Since we assume the media is good and we don't want to buy a new drive if it isn't necessary I would try the connections and cable route...just to rule that out as well.