My text on a Nancy Drew game is boxes?

Okay, I downloaded Nancy Drew "Trail of the Twister" from BigFish, and when I tried to play, all of the text (like closed captions and game instructions) were covered by blocks. You could just see the boxes/blocks and you couldn't read the text. This has happened before and I had to download some thingy on my computer, but I can't remember what. Can someone please tell me how to fix the text so I can actually read it? Thanks :)