Welcome to MyCE! :flower:
Did you ask your friend how to do this properly? For one thing, Memorex DL media doesn't work that well with most burners. Unless you have a burner that can handle them, you're always going to have problems.
The only DL media guaranteed to work is Verbatim.
What is the brand name and model number of your burner?
What is the rated speed of the Memorex DL media?