Maybe you should read HOWTO: Ask (and Answer) Questions

As I said before "Windows XP does not have built-in support for writing DVD's and therefore doesn't recognize a blank DVD as anything more then a CD" so if you were writing to DVD's in Windows XP then you had to have installed some software that was not a part of Windows XP in order to do that. Now if you did and you are having a problem writing to DVD then you need to state that as the problem not just say "it plays DVDs with data on them, but does not recognize DVDs that are blank" so if that is the case then read HOWTO: Ask (and Answer) Questions and provide the relevant information as suggested in that document in order for someone to provide additional help base on explicit and specific information without having to guess at what the issue may be.