Windows 10: Unknown Account In C Drive's Security Tab

I have got Unknown Account in my C driver's Security Tab...I removed that, but when I restart My PC, again it comes... Sometime My PC take long time to Open, and when I Open MS word, it doesn't open, I have no access to install or uninstall a program....please help me.

:)

 

Account Unknown has full Security permissions on my own User - huh?

Brink - thanks for suggestion.
But I'm not sure about this at all.
By the way, if I open a cmd and do the wmic (or wimc?) command to show all the accounts, this unknown one does not appear!
What's the worst that could happen if I delete this unknown account from the security tab?

 

Local disk C Security Tab

Hi,

Administrator account will grant you access to change security settings, installation of programs, accessing files on the computer. We suggest creating a new administrator account user by following the step on this
article to resolve your issue.

Note: Once you created a new administrator account user, you can grant your primary user access to drive C.

If anything comes up, don't hesitate to get back to us anytime.

 

C drive inaccessible

Hi Paritosh,

Thank you for giving us an opportunity to assist you with the query.

Apologize for the difficulties that you're experiencing in Windows 10.

Please be assured that we will do our best to help you.

• 
  Have you logged in as an administrator?
  
• 
  Have you made any changes to the computer prior to this issue?
  

An "Access Denied" error message can occur for one or more of the following reasons:

• The folder ownership has changed.
• You do not have the appropriate permissions.
• The file is encrypted.

Before we could reset the computer, let us try the following steps, and check if it helps.

Step 1: I suggest you to follow these steps to take the ownership of the drive.

• 
  Right click on Drive C and click
  Properties.
  
• 
  Switch to Security tab, click Edit and
  Add to add your user account, if it is not listed. Assign the
  full control permission for your own account and click OK.
  
• 
  Click Advanced, switch to Ownership tab and click
  Edit button.
  
• 
  Highlight your user account and click
  Apply, and then click OK.
  

Step 2: Let us try to disable to UAC settings and check.

• 
  Press Windows key + S and type
  User account control.
  
• 
  Select Change User Account Control Settings.
  
• 
  Move the slider to Never notify and click
  Ok.
  

Refer: "Access Denied" or other errors when you access or work with files and folders in Windows

https://support.microsoft.com/en-us/kb/2623670

(Applies to Windows 10 as well).

Hope it helps.

Let us know the status, we are glad to assist you further.