Very funny thing. I have the exact same DVD rom. Eh..myne is black. By the way, do you perhaps have a DELL machine? Ok back to buisness. First what you might try is system restore. Maybe you have accidentely messed something up without knowing it. Don\t worry it can happen to anyone. You of course need Win XP to use System Restore.
Go to Start then to All programs, Accesories, System tools and activate SR. Select the checkpoint, a few days before would be most recommended. Do what it is asked of you and try reading your DVDs again AFTER you prperly restarted your PC. If that doesn't work, send it to the dealer, shop where you bought it and explain your problem. If the CD is dammaged and you have a waranty on it, they should replace it for you or at least repair it.