=?Utf-8?B?TVJE?= wrote in
:

I did as you suggested but after signing in as the built-in
administrator I was not allowed to open the Users option in the
control panel. Access was denied. Anything more I can do?
Thanks.

It sounds like you have an access / security problem.

You might try to see if you can restore to a point before you changed
permissiors.
Boot to Safe Mode
Start-Programs-Accessories-System Tools-System Restore

If this doesn't work, hold your breath and try this:
"How do I restore security settings to the default settings?"
http://support.microsoft.com/kb/313222

HTH,
John