ARCHIVED: In Windows, why should I avoid running my computer as an administrator?
Operating your Windows computer as an administrator (or Power User) leaves it vulnerable to security risks and exploits, such as Trojan horses. Simply visiting an unfamiliar Internet site as an administrator can cause extreme damage to your computer, such as the reformatting of your hard drive, deletion of all your files, and creation of a new user account with administrative access.
To avoid these problems, the University Information Security Office (UISO) recommends that you refrain from running your computer with administrative rights and instead practice the principle of least privilege (you will still need an administrator account on your computer to perform system maintenance; see At IU, in Windows, how do I give myself or other users login privileges on my computer?). For more, search the Microsoft Help and Support web site for article 825069.
To perform tasks that require administrative privileges, you can temporarily log in as an administrator; see Wikipedia's User Account Control page.
This document was adapted from the Microsoft TechNet article Why you should not run your computer as an administrator.
Last modified on November 16, 2012.