Performance :: Slowdown Of System - High CPU - Cannot Find Source

I opened my computer after having it been asleep all night; everything was working fine until I realized that my sound volume was stuck at a high level and no matter what I changed the volume to, it would not go down. Having had issues with my sound drivers before, I solved this by reinstalling the sound driver. I figured this would be the end of my issues for the day and restarted the computer to finalize the installation. Then windows installed updates, and when I got back into the system, I realized something was wrong. I have Advanced System Care 9, which comes with a real-time monitor of system usage (RAM and CPU), and I noticed that the CPU usage was much higher than it should be--usually it will be around 1-5% when I am not running anything (or just a few programs), but instead it was using 20-90% CPU, and the RAM would not go any lower than 24%.

However, I had had this issue before; Bitdefender Antivirus had started acting up a few days ago using up 90-100% CPU, and I had caught it using Microsoft Process Explorer. Removing Bitdefender solved the problem. So, naturally, I went to the process explorer to check what was using so much CPU again. But this time--nothing. The windows process explorer showed nothing using that much CPU. From there, I began to notice the rest of the problems: many functions of the task bar would not work, such as any of the toolbar icons, or the windows icon, or Cortana. Firefox would not open, either, and I could not get Steam to connect.

Also Ctrl+alt+delete did nothing but bring up an endless black screen, as did restarting. The only way to reboot is to force it by pressing the power button. Therefore I could not reach safe mode. From there I ran a myriad of virus/malware/adware scanners/cleaners/optimizers, none of which found or did anything to fix the problems, though my computer is now squeaky clean otherwise! Eventually I managed to get into safe mode by a very finicky method, which was by turning the computer off during startup which made it do a startup repair next time it turned on, from which I was able to enter safe mode.

And in safe mode--everything works. None of the described issues happen there. I am able to use all the windows features (aside from those blocked in safe mode), ctrl+alt+delete and restarting function properly, and I am able to connect to the internet and use firefox, everything works. So this means that there is something there causing the problems, and it is being blocked by safe mode, but I cannot find it! After running several more scanners, all of which found either nothing, or only small innocuous things, I ran Microsoft Safety Scanner, which found a "severe" trojan which was (I believe) called Dynammer!ac, and I figured this must have been the culprit--but no. Restarting and returning to normal mode resulted in the same problems occurring. Since then I have uninstalled/reinstalled a few drivers that were suggested to me to try, such as sound (the one that I had to replace before the problems started), and the display drivers, none of which fixed anything, either.