Excel and Powerpoint try to reinstall every time

I'm working on a PC running XP Pro/SP2 installed with Office 2003 Standard.

Office 2003 came with the PC from Dell. I looked up my invoice and the full
version came with the system, but now when it comes up, it says it's the 2003
Standard Student & Teacher edition

Sometime back, the full version of Powerpoint was installed and it functions
properly, but now when I launch Excel or Powerpoint, it initiates the install
process. If I click CANCEL, it stops the process and lets me use the
application normally.

I looked it up in Event View and it mentions a registry key is missing:
something like
hk-current-user\software\microsoft\office\11.0\userdata is missing.

How do I correct this problem?

Is there a log file I can view that specifies the install history of all
Office products so I can verify what was products were installed and when?

Thanks,

Tony