1. First, it helps if the web browser is already open and have the window set to resize instead of maximize; it can cover most of the page, as long as there is an area in the background to click.
2. Then when you click on the link, it will bring the browser window forward.
3. When you are ready to go back to the PowerPoint, just click in the background.
4. If for some reason, the browser window was already maximized, then click on the Restore Down button to see the Powerpoint in the background, which you can click on.
5. Clicking on the Task Bar Slide Show link can also work. Just make sure you don't click on the Presentation link.