Does PowerPoint start every time you start your computer? You can try this:
1. Right-click the START button at the bottom left.
2. Click "Explore"
3. Click the "+" sign next to "Programs"
4. Click on the "Startup" folder.
5. If a shortcut to PowerPoint appears in the window to the right, delete
it.
6. Close Windows Explorer out and re-start your computer and see if that
fixes it.