Quote Originally Posted by eastman View Post
You can also try booting in safe mode and seeing if the slowdown persists. If you can load the recovery screen on boot, you might even be able to get to the Windows Reinstallation screen and reinstall Windows from there (also found in the settings application). This option was pretty useful when my laptop nearly lost EVERY (not even kidding) file and setting, while on the same installation and Microsoft account. If anyone is running Kaspersky on their computer, it is probably the Windows 7,8,or 8.1 version. When my laptop updated, it was still running the 8.1 version of Kaspersky so I decided to update it to the Windows 10 version. The updated seemed to go fine, until the computer restarted... The initial log on process took way longer than normal and when it logged me in, all my files were completely gone, 100% missing. Somehow my applications and programs still showed up in start, but not in the uninstall menu in Control Panel. I tried to run a program from start and my system basically died, from normal speed to super slow. Nothing was working, no task manager, no settings, no control panel, no win + x, using start to shutdown was futile, sleep key wasn't working, nothing. The power button refused to work as well, leaving me with no option but to unplug the battery and charger from the laptop and cut the power. Upon restarting, the computer was in the same condition, I uninstalled Kaspersky and tried booting again, but the situation was the same. File History was not restoring backed up files either, so I just reinstalled windows from settings (which worked if I didn't try to run a program) with the option to keep files but uninstall applications. After the reinstall all my settings and files were fully restored and were opening and all that, though no programs were installed due to the Windows recovery option I selected. After redownloading all my programs I was hesitant to install Kaspersky again, but I tried anyways. When reinstalling Kaspersky again it did not break my computer this time. After some digging around with log files, I discovered that a critical error occurred during the Kaspersky update, which caused a critical failure during the boot sequence. The critical failure during the reboot was caused by Kaspersky's error, which, in essence, disabled Windows' ability to read from the drive (causing the file and setting loss, as well as the CPU overload when trying to load applications it didn't think were there). The error caused by Kaspersky essentially broke Windows, which is why the reinstall worked as it fixed windows. When I reinstalled Kaspersky after Windows installed again, it wasn't trying to update a solidified program (like before) and instead installed Kaspersky fresh onto the computer causing no errors.

likely your problem originates with whatever Antivirus you are using, whether its an old version with compatibility issues or an updating issue like my experience was.
I plan to look over this more in depth tomorrow when I have more time, but in the meanwhile how do I boot in safe mode with Windows 10? I've done it before on pc's running older versions of Windows, but when I tried that method today it brought up some menus I was not at all familiar with. Thanks!