Boot safe mode, head to device mangler and uninstall the CD/DVD drives there. Exit, reboot and it should add them back in.
my liteon ldw 815s will not recognize blank dvds when inserted. it claims they are cds which i cant access. The only recent changes were windows updates. I have tried different types of media, updated firmware and did the upper and lower filter deletes in the registry as microsoft suggested. The burner works fine in my other box. I have nero and sonic and when i try to burn a dvd it says to insert media!