Well, I have to format my HD and re-install may O.P. Now my DVD ROM/R/RW can read and write CDs, but it isn't reading and writing DVDs...
I' using Windos XP SP2 Professional and my DVD/CD reading and writing hardware is TOSHIBA DVD-ROM SR-R6012

XP in itself has no DVD support to read or write DVD's.

You must have had some DVD software installed and you will have to reinstall it or find a new program.