What media are you using?
There is a great deal of crap and brand name knockoffs out there for sale. Never buy from Staples, Office Depot, Best Buy.
I strongly recommend using only JVC (Taiyo Yuden) or Verbatim (Mitsubishi) discs purchased from a reputable house:
Amazon, Newegg, or SuperMediaStore.
Since I started following this protocol 7 years ago, I've had only two coasters