shiranbi

Hi I have NEC AD-7170A dvd burner. It used to work just fine, lately it has stopped reading some of the dvd's. I have formatted my comp and know that it couldn't read at least one dvd before (am not sure about the rest). It recognizes the dvd, its title and everything else but it says that its total size is 0. The dvd's that it does read are a movie dvd and games dvd's. All dvd's that I burned or my friends it refuses to read (All of which are data or iso dvd's). All of my dvd's including the ones that it does read are -R. The only difference i could find between the dvd's that it does read and the one's that it doesn't is the supported speeds, in the ones that it does read its 2-4 and the ones that it doesn't its up to 8 or 16. As far as i can tell, it reads all cd's I have tried the dvd's on another computer and they are just fine. I have uninstalled and reinstalled nero with no result. The burner it self is not that old. I have xp sp2. Anyone has any idea what I can do? Thanks