I would check one of two things. Make sure you have the latest firmware for your burner and check the DVD+RW media that you are using. Sometimes low quality media has a hard time being recognized by certain burners. I recommend Verbatim media. I have been using Verbatim for about three years and not one Coaster, including DVD+RW media. Hope this helps!
See if you can find the MID code for the Sony DVD+RW discs. If the code is not recognized (and Sony is not one of the brands "recommended" by Samsung on the web site whose link you provided), then the discs won't work no matter how good they are. You may have to buy only those brands listed or the brands that use the manufacturers who are listed (CMC, Ritek, Taiyo Yuden, and Prodisc are a few examples of the manufacturers).
