My computer won't recognize my TV

Hi,
I recently had a virus and had to reinstall windows. I had Windows 2000xp but then my boyfriendinstalled Windows 2000xp professional was installed over top of it. Now when I try to play DVD's from my laptop through s-video onto my tv, my computer won't recognize that it is connected to my TV. I've reinstalled nvidia but still nothing. any other ideas? HELP!!
thanks!