Can't download anything...

[Phantom of Krankor]

I've got a brand new computer, but this hasn't worked on another computer in the house also. But when I tried to download the Sixth Sense rifftrax for the riff player, it would finnish downloading and this thing comes up saying "file could not be downloaded because windows needs to know what file created it" and I have no idea what to do. I've tried it on other movies but nothing downloads. Please help!!!

EDIT: And another thing, downloads for Divx rifftrax on demand works! I don't get it. Someone please help!