PPS files are PowerPoint Show files designed to start the presentation as soon as you double-click them. If you double-click a PPT file, the presentation is opened in PowerPoint in edit mode. Because double-clicking a PPS file plays the presentation automatically, many people think they can't edit it. Don't worry -- you can edit the presentation in PowerPoint and even save it as a PPT file. Furthermore, you can save your own presentations as PowerPoint Show files.
Converting PPS Files
To convert a PPS file to PPT, open it in PowerPoint. You need to launch PowerPoint first, then press "Ctrl-O" and select the PPS file to open it in edit mode. Edit the presentation using PowerPoint's built-in set of tools, if necessary. To convert the file, click "File" and choose "Save As" from the menu. Click "Browse," select "PowerPoint 97-2003 Presentation (.ppt)" or "PowerPoint Presentation (.pptx)" from the "Save as type" drop-down box, select the destination folder and click "Save." To create a PowerPoint Show file, select "PowerPoint Show (.ppsx)" or "PowerPoint 97-2003 Show (.pps)" from the "Save as type" box.