Does Firefox save a file, or are you getting the gibberish before Firefox does the download? '''''If you get gibberish in a tab:''''' The server might not be identifying the file correctly. Some servers tell Firefox that various unknown files are plain text, which Firefox will display in a tab. What a mess. One possible workaround is to right-click the link to the file and choose "Save Link As..." to force Firefox to save the file instead of displaying it. If it's not a link you can right-click, I can mention an add-on to help with this problem. '''''If the problem is after the file is saved:''''' Does the presentation open in PowerPoint, or in some other program? ''If the presentation doesn't open in PowerPoint:'' One possible reason is not having the correct file extension. The normal file extensions for PP presentations are: * .ppt (older format) * .pptx (newer format) If your Windows hides these file extensions on PP files, you can set it to show all the file extensions. This tutorial covers the steps: https://www.bleepingcomputer.com/tutorials/how-to-show-file-extensions-in-windows/ Does that seem to be the problem, or is the problem after the file opens in PowerPoint?