unknow user

[ephroon]

I need urgent help please I'm facing a terrible problem
*in the security tab I found a new user called unknowns(1-5-21......who owned my partitions I replaced the owner to me and disabled inheritance and I could successfully remove this odd user , the surprise was when I installed a new copy of windows 7 I found this unkown user a gain in my security tab users ....please tell me how to get rid of it permanently?
thanks alot

 

[Core]

That number is a security identifier. The system uses it to locate a user account. In most cases, these accounts are created by the system. Many times the SID refers to an administrator account.

Sometimes, especially if you do an upgrade, you may find that a partition or an external drive cannot be written onto because you don't have privileges, whereas you should. In this case, what is usually sufficient is using takeownership.reg to enable Take Ownership in the context menu (right-click menu), selecting the root of the offending/inaccessible drive, right-clicking & selecting Take Ownership (in Windows Explorer). This associates the drive and its contents with the current account.

Once you have taken ownership of the files/drives, you may be able to remove the account with the SID that bothers you, but in most cases it's unnecessary, or the system may recreate it.

The SID typically starts with S-1-5-21 or similar number, followed by a long list of numbers, and then a hyphen, and either a 3 or 4 digit number. If you look at the last number (3 or 4 digit) it can tell you what kind of account it is. 5xx-numbered accounts, for example, are created by the system by default and are harmless, while four-digit numbered ones are not created by default.

 

[ephroon]

I'm still wondering

thank you very much in advance "Mr.Core" for your kind reply,takeowner.reg is a good idea but I still wondering why it appears after changing windows ? ,keep in consideraton that this user is a new one I can't remember that I've seen it before
is it a virus? or what? and how can I remove it permanently?