Post-update Windows program problems

I ran the Windows (XP) Updates yesterday and when my machine restarted, I
could not access any embedded Windows programs: My Computer, Explorer, System
Restore, Help, etc. I can access other programs, including Microsoft Word,
etc. The problem only occurs in the Administrator account and not in a User
account. I managed to get the System Restore to work by stopping the
"explorer.exe" process, restarting explorer through a "New Task" under the
Windows Task Manager, and then starting the System Restore program. I
restored the computer to the previous save point, but still have the same
problems. I tried booting from the Windows XP cd, but no options work (e.g.,
Restore); I end up having to shut the computer off and rebooting. It is
running XP SP2.