I'm curious. On my Windows XP desktop, right up till Thursday, April 16 2016, I had no issue updating Microsoft Security Essentials. When an issue came up, I attempted to download an installer produced by Microsoft specifically for the program that would force updates through in the case of issues with the actual updating system for MSE. However when I attempted the download, I didn't get all of it. The file is a 111mb file, but Firefox was only getting 110 of it, which rendered it useless. I haven't gotten around to updating from version 28.0 on my XP machine for two reasons; 1) I'm working on backing up all my stuff to migrate to a windows 10 laptop in case this old monster of mine crashes and burns and, 2) I have still yet to learn how to move the data over to my new machine so that I can have the older version of Firefox be separate from the more updated versions on it (or the variants, such as Waterfox) despite my best attempts to learn how to do so via links recommended here. Does anyone know if having an older version of Firefox has somehow affected MSE's ability to update somehow, and/or if the older version also somehow affects downloads?