Microsoft Office 2000 programs, including Excel, contain a command line called Detect And Repair, which checks and fixes problems with Office program files, DLLs, and registry settings. (This utility does not affect worksheets or other document files.)

Detect And Repair, which you access as a command line option of the Setup utility, performs the following actions:

• Reinstalls Office .exe and .dll files if missing, out-of-date, or corrupt
• Reinstalls all Windows Installer shortcuts, overwriting any existing shortcuts
• Rewrites all required local machine registry values
• Rewrites all required user registry values
You can run Detect And Repair from within Office, but that won't do much good if a serious error is preventing your user from even launching an Office application. Fortunately, you can run the utility from the Run dialog box with the following entry:
drive:\setup.exe /focums install.msi