Hello please please can some one help me i am operating xp pro and i am the administer but when i log in i can not use add or remove programs and the log in screen has changed from the original

What happens when you click Add/Remove Programs?

What Login screen did you have (original)? Welcome? Passwaord? etc.

Possible fix:

'Restore XP's Welcome/Logon Screen'
Under Win XP Fixes- http://www.dougknox.com/

If this is a new problem you could also try a System Restore:

Start/Run/ %systemroot%\system32\restore\rstrui.exe