after re-reading what you posted, it seesm like you already tried safe mode.
First off what OS you running? If Windows Xp, read this http://articles.techrepublic.com.com/5100-...11-6112906.html
taken from the link:
You can make it more difficult for unauthorized persons to get into your system by renaming the Administrator account. Follow these steps for a Windows XP Pro machine:
1.Go to Control Panel and open Administrative Tools. Double-click the Local Security Policy.
2.When the Local Security Settings snap-in appears, open the Local Policies\Security Options branch and double-click the Accounts: Rename Administrator Account policy.
3.When the Accounts: Rename Administrator Account Properties dialog box appears, type a new name in the text box, and click OK.
Follow these steps to rename the Administrator account in Windows XP Home:
1.Press [Windows]R to access the Run dialog box.
2.In the Open text box, type Control userpasswords2 and click OK to access the User Accounts dialog box.
3.Select the Administrator Account from the list and click the Properties button.
4.In the User Name text box, type a new name, and click OK.
Note: This tip applies to both Windows XP Home and Professional editions
Edited by Derek Ellis, 02 June 2009 - 01:59 PM.