Here's a link for the specific error you're encountering:
http://answers.microsoft.com/en-us/...80072efd/398546d2-6b6d-47a0-b075-82d815fa9a8f
Basically, you need to install the latest Windows Installer. You can Google that easily. With the wrong installer, you can't install the WGA verification tool, and hence can't update.
After doing the steps above, Windows Update has found a total of 150 security updates.
This cured all my update issues, (couldn't update), but I was dealing with an XP box.
You should be able to simply kill Windows Defender in task manager, at least temporarily.
iTunes is also known to semi-brick Windows machines. Apple planned it that way.
M$E, has been getting terrible reviews because of its wretched detection and disinfection rates. In short, just because M$E says you don't have an infection, doesn't mean you don't have an infection.
IMHO, "Malwarebytes", is as useless as t*ts on a boar (Your results of course, may vary).
The temperatures on your machine, are not only "OK", they actually seem stellar, very low.
Since none of our suggestion have helped in any way, and you're adamant we're wrong, and the problem is a hardware issue with the CPU or the board, just go out and buy a new computer. That's about all that would settle those issues.