Windows 7 extremely slow doesn't turn off

Jan 4, 2019
Hello there,
I am working on a PC of a friend that doesn't turn off, the screen shows "Shutting down..." but nothing happens. It works really slowly and internet doesn't work properly (the ethernet card can't get the IP address from the DHCP server).
I tried these solutions so far:

    Restrore to previous restore points (from safe mode): the computer keeps working with not success (I let it work all night);
    I used SFC Scannow but no issue was found;
    I used CHKDSK /R /F but no issue was found;
    I tried dism /image:C:\ /cleanup-image /restorehealth, everything seems normal;
    I connected the drive to another PC to check for virus, the disk seems clean;
    I tried to boot disabling all the non Microsft software and services, it made it worst, since after login all I see is a blank screen (in black). I also deleted the files from C:\windows\prefetch and C:\windows\temp.

I can work on safe mode well to find a solution.

My friend told me that it happened after upgrading a software he uses, but I remember the PC was very slowly before and it should get me to a restore point with ease.

Thank you so much for all the help you can give me.