I bought a 50 pack of Ritek-s04-66(Memorex) DL media with a Plextor 800a last week. Didn't bother checking manufacturer's recommended media because I never had media problems with single layer on my Plextor 712a. Big mistake. Went 0 for 5 using my old tried and true software then stumbled on ImgBurn and this forum. My first burn with ImgBurn was a keeper. Followed this with 3 more losers. I'd assume the main problem is with the layer break since failure would happen at the half-way point of burn. Bought 15 pack Verbatim 8x and am 1 for 1. I want to thank everyone here for their helpful posts, especially LIGHTNING UK!. Oh, and of course thanks to ImgBurn which is a slick piece of software.