When you open, Windows Installer keeps prompting?
If so, try the following:
1. Open Task Manager
2. Start > Run and enter in excel /safe
3. When Excel starts, kill all processes named
msiexec.exe. If msiexec.exe restarts again, kill
it.
4. When all msiexec.exe are gone, close Excel.
5. Open Excel.
6. Retry Step 5 with all other Office programs.
You should no longer see the Windows Installer prompt, however,
you may be prompted to re-enter some personal details (only
one-time annoyance)