Need 'vids:div3' decompressor

[Jag7577]

I am trying to play a Movie on my computer but the message "cannot find 'vids:div3' decompressor" Keeps popping up. What do I need to do? Is there a place where I can find this Codec? And what do I need to do after I find it and downloaded it?
I have a Gateway computer 550
PIII
I have been trying to play it on Media Player

Love the site
Thanks In advance

Gerst

[UncasMS]

that's divx 3.x