1. Check that your PC has been recently reset. Find the uptime. Windows NO LONGER (8 on) adequately resets the PC on a "shutdown". You need to "Restart". Just disable Fast Startup forever.
2. Running magic "fix it" software downloaded for FREE is in my view asking for trouble.
3. Check system file integrity by running in an administrator cmd window
chkdsk /f
then sfc /scannow
If either of these show errors that are not automatically fixed come back for more advice with DETAILS (screenshots).
4. Make sure you are only running ONE anti-virus program. If on Win 10 or later use windows defender ONLY.
5. Try a different user. Make a new one.
For anything more you are going to have to come up with a LOT of detailed info. You may well get better help elsewhere.
Windows version, memory size, hdd or ssd... ... ...
Is CPU high, is disk utilisation high? Is there any free memory?