It's good to find this site as I'm hoping solutions will be available. I have a XP desktop (SP3) and Firefox ESR 52.2.1 is presenting with connection errors to common sites such as Outlook.com/ LinkedIn/ Yahoo and others. Your site came up in a google search and after reading Monroe's thread titled 'Browsers Still Working with WinXP in 2017' it was clear I was not alone in this situation. I would upgrade to a new machine/software but that is not possible at this time if you get my meaning, so I'm trying to see what can be done to preserve internet access. I tried SWiron and Sea monkey but they would not install on my OS. I DL'd 98SE's archive of Opera in hopes it will install and run on my machine.
If anyone reading this has some suggestions, I'm open. Thanks to the persons behind this site and I hope to hear from you.