A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
I'd first restart your computer. Quit Windows entirely, restart and try this again.
When you try it again, start PowerPoint from the Start button then use File, Recent to open the file. Don't use Windows explorer to locate and doubleclick your PPT file's icon. Sounds odd, I know, but there's a reason.