Too often a colleague or student will attempt to give a presentation and the PowerPoint deck will fail (for any one of a million reasons). I’ve never had a class of 15 or more students where every presentation ran properly.
I’ve started including in presentation assignments that students should “prepare a slideshow presentation, saved in .ppt format, then export it as a .pdf and a series of .jpg images, all of which should then be emailed to yourself and another classmate (and sometimes me), uploaded to Google Drive, sent to Dropbox (write the download url on your arm in Sharpie), copied onto a flash drive which you keep on your keychain and burned onto a CD-ROM.
I let them know that I won’t be checking to make sure they took all these steps, UNLESS they tell me in class that they can’t give their presentation.
The best part of this system and the way the universe seems to function: if you have your presentation available in several ways, the first attempt will always work. If you show up with only one copy, it’s likely to fail.