Samsung DVD\CDWriter combo

Hi dear ones,
I am having a problem with a samsung dvd/cd writer combo given to me by my friend. In deed i am using winxp service pack 2, Compaq desktop presario 533mhz with 256mb ram and 60gig hdd. My problem is that the dvd cannot play back a movie. It reads all right, but each time i want to play a dvd movie it talks about the region. I have gone or tried to change the region but its like my friend have changed it several times that it cannot be changed again . Is there a way I can beat up this problem and use this dvd fully. it is really new. I'll be most grateful for any clue