dvd burner burns cd but not dvds anymore

i have a dell d810 with a philips sdvd8820 drive. i was able to use nero and copy a dvd or use dvd shrink and copy a dvd fine until a couple of days ago. now it only burns cds and gets about 1/4 of the way through a dvd before it says burn failed dvd write error and stos. every time. i have uninstalled nero and installed it back and that did not solve the problem. please help