Pictures included in PowerPoint presentations created on the Macintosh do not always show up on Windows computers. This is what I’ve learned… (if you have more/better information, please let me know.)
Graphics on PowerPoints created on the Mac often show up as white blocks with the message: "quicktime and tiff decompressor needed". This is neither an ASD computer problem nor a Quicktime problem. Evidently when graphics are copied from Safari to the clipboard to PowerPoint, they are automatically compressed in a format that Windows operating system cannot read. This problem can show up in Microsoft Word documents also.
To create PowerPoints on a Mac that are compatible on both platforms
Best Practices: Create a folder for your PowerPoint project. Create a new PowerPoint presentation and save it in the folder. When you find a graphic that you wish to include, save it in the folder, then import it into your PowerPoint. This gives you the raw material in case you wish to use it again, later. Use any browser, including Safari.
For further discussion, see the Tech Help pages - PowerPoint