1. Check your file name and file format.
2. Check whether the images are inserted or linked to external files.
3. Verify that the images are in the same folder as the presentation.
4. Ensure that the image file type is fully supported.
5. Make sure the images are optimized for the presentation.
6. Check the size of your images to make sure they will fit on the slide.
7. Ensure that the images are up to date and have not been altered.