Wesociety has it exactly right.
I've lost track of how many people I've heard buy the NEC 2500A because it was a good burner for little money, then also buy el cheapo media, and expect the drive to work miracles with it just because reviews say it has excellent write quality and compatibility. Then they get upset either because the media has errors because of its poor quality, or because the drive doesn't burn the media they chose out of spec at 8x. That's like buying a CPU as cheaply as you can, then bitching when it doesn't overclock another 300MHz.
The first thing almost every computer class I ever took (and that I learned when starting out as a tech ten years ago) said about data was GIGO - "Garbage In = Garbage Out". Buy media that is known to have a good record (i.e., Ricoh, Taiyo Yuden, and some others) and you won't have issues. If you want 8x capabilities, buy true 8x media that's on NEC's certified 8x list, don't gripe when your 4x media doesn't burn beyond the capabilities it's spec-ed for.
LoneWolf (Happily burning Ritek G04's at 4x just fine on his NEC, and they read great too, on everything he's played them in)