Fixing issues on Windows 11

Computer boots but opens Windows very slowly and you get a "Cannot log onto account" message

this suggests that your Windows user account (and perhaps system files as well) has been corrupted and Windows has made a temporary account for you
- do not save any files into this temporary account as they will be deleted
try to back up your files from your usual Windows account:
- in File Explorer, go to C:\Users and select your usual Windows account and hopefully you can get access to your files and copy them to an external drive (if this is not possible as USB has been corrupted, copy them to a new folder on your C: drive which will be outside of your Windows User account
try to repair your Windows system files
- turn off any antiviral software temporarily
- open up Command Line as Administrator:
  - in the Windows Search field type cmd then when Command Prompt displays, right click and select Run as Administrator
  - in the command line editor window, type:
    - sfc /scannow then hit Enter
      - if this finds corrupted files but cannot fix them:
        
        type DISM /Online /Cleanup-Image /CheckHealth then Enter
        
        when finished, type DISM /Online /Cleanup-Image /ScanHealth then Enter
        
        when finished, type DISM /Online /Cleanup-Image /RestoreHealth then Enter
        
        when finished, type sfc /scannow then hit Enter
        
        if the DISM failed or the repeat sfc still cannot repair the corrupted files then you have several options:
        
        1. run DISM again but use a Windows Installation Media on a USB drive (you will need to create this perhaps on another computer by downloading Windows Media Creation Tool), and type DISM /Online /Cleanup-Image /RestoreHealth /Source:wim:D:\sources\install.wim:1 /LimitAccess then hit Enter (REPLACE D: with your actual USB drive letter)
        
        2. use Windows Update to try to repair the files:
        
        back in Windows, go to Settings Windows Update and select Use Update to Repair
        
        3. try rolling back Windows state to a previous RESTORE point
        
        unfortunately, Windows does not automatically create the restore points you need so this may not be useful if you have not manually created one
        
        4. try repair by booting from a Windows Installation Media on a USB drive
        
        this gives you a variety of options
        
        NB. run chkdsk /f or chkdsk /r only if you suspect drive or file-system corruption, bad sectors, or persistent disk-related errors.
- once repaired, restart the computer and hopefully you will get back into your usual Windows user profile and not a temporary one
- worst case scenario, you may need to re-install Windows but this may lose your data if you have not backed it up!

Computer boots but running very slowly

it may be running a background Windows Update
- go to Settings:Windows Update to see if this is running
- WARNING: powering the computer off during this can lead to corrupted Windows system files and then you will need to repair them as per above section!
you may be running out of hard disk space and computer is not able to create enough virtual RAM
- go to File Explorer, click on This PC and check the free space for the C: drive
  - if there is not much space, free it up by removing temporary files and unnecessary files (consider moving files to an external USB drive)
a different back ground task may be running
- press Ctrl-Alt-Delete and then choose Task Manager to see what processes are running
system files may have been corrupted
- go to the previous section on how to repair corrupted files