Help Please

I never had any trouble playing any DVD's before my computer went into the shop and got a new motherboard about two months ago.

So my husband got me Avatar as a present and tonight I popped it in my DVD LightScribe DVD Writer thing and all the prompts came up asking me which option I wanted to open up the DVD with.

I chose Windows Media Player (because that's what I did in the past).

Well, I get a message "Windows media player cannot play DVD because a compatible DVD decoder is not installed on your computer".

It then gave me a "web help thing", and I clicked on it and it took me to a Microsoft thing that said it could check my computer and see if I have a decoder installed, but I have to click on continue and get validation.

It prompted me to download something that would, I guess, tell me if I have this decoder thing or not.

I have a HP Media Center PC. I NEVER have had a problem playing dvds.

When I pop in this Avatar it gives me other options besides Windows Media player. I tried all of them.

Nothing works. I clicked on the "Real Player" option and I got this screen saying there are two versions. A $39.99 real player and a free two week version".

What the heck is going on?

All I want to do is play my Avatar.

Help pulllleeeeeze.

Melody

P.S. I pulled out my old portable dvd player and I'm watching Avatar. I don't care how small the screen is, I ADORE THIS MOVIE. It puts me in a whole different zone. Very calming

But I WOULD really like to know what happened to my lightscribe dvd player thingee