I download a lot of PowerPoint presentations and recently I am seeing more and more are stating they need repairs when opened!
Unfortunately repairing does not work and downloading them again doesn't help either! What is happening is that Windows is detecting that these files are from the Internet and enabling a block on them for your protection. To remove this block, you need to right click the file, select Properties, click the Unblock button and click OK.
You will then be able to open them successfully.
Thanks Joseph for spotting the type-o in the original post.