I have a Macbook, and I'm trying to download the powerpoint viewer (I need to use powerpoint, and I don't have enough to buy the actual program). I've clicked the download button, and it downloaded, but it didn't actually work. The powerpoints I try to view say that the file is in a truncated form or something, and whenever I click the powerpoint viewer program it immediately goes to text edit. What do I do? I need these powerpoints to study for my final tomorrow....