I Personal burn on low speeds depending on DVD-R & DVD+R I buy My 8X disc I burn on 2-2. 4x And let me say they come out beautiful Not one glitch.
Now The 16X Disc which i personal don't like. But i will used them if i have to (to much firmware problems with 16X for me) I burn them on 1X & they come out beautiful.
Maybe try a lower speed... I have a 16x Burner but it dosen't mean i'm going to burn my movies 6X 8X 0r even 16X Because i know how some DVD Players are they will spit them out as unreadable 75% percent of time for me... I hate to gamble with bad odds like that.
But like i said if you want try a lower speed. it works great 4 me...