I am running an IBM ThinkPad 31P with Windows XP Pro. On 11/18/17 my computer updated Firefox automatically to 52.5.0 ESR even though I have it set to ask first. Within minutes of the update my CPU usage spiked to 100% with no programs open. Windows Task Manager showed svchost.exe to be at 98%. This same thing has happened with every major Firefox update and issue has not gone away until Firefox issued an update to resolve instability issues. This time I exchanged hard drives to my "back-up clone" and immediately started removing Firefox program. However, I neglected to disable my wireless card and almost immediately I got a "Firefox Updating" message on the screen. I immediately killed the computer, removed the wireless card, rebooted it but damage had already been done and CPU usage spiked to 100%. Using software removal tool gave message that Firefox had already been removed. However, I was able to locate the new program in my Temp Download file and manually remove it. This did not resolve the problem. svchost.exe CPU use spikes to 98% or higher by the time computer has booted up, with no programs open and internet access deactivated. Have attempted to use my "Autoruns" program to troubleshoot and determine the cause but am not proficient enough. Am at the point now of planning to reformat a 3rd hard drive with Acronis clone from my stand-alone backup hard drive, which has not been connected during any of this, then removing Firefox permanently and switching to Opera. Any thoughts on what might be causing this problem? Thanks!!!