When I click on a shortcut on the Start menu or the Desktop, it doesn't work. I can't open Help and SUPPORT or search. When I try to launch certain programs I get an error message that says "App Name" cannot be found, please be sure you have spelled the name correctly, etc. Internet Explorer loads only "Customize Addons" and won't navigate anywhere. I can't start any program or utility like "Backup" or "Format". Some programs open when I RIGHT click on the shortcut and highlight "open" Enter, but only a few, like Microsoft Works.If you have the original Windows Disc(s) you can perform a repair INSTALLATION which MAY correct this. Sounds like a corrupt registry to me where paths are broken. But a repair install will FIX more than just registry problems if any exist.Do you have an XP CD?

If so, place it in your CD ROM drive and follow the instructions below:
•Click on Start > Run and type sfc /scannow then press Enter (note the space between scf and /scannow)
*Let this run undisturbed until the window with the blue  progress bar goes away
SFC - Which stands for System File Checker, retrieves the correct version of the file from %Systemroot%\System32\Dllcache or the Windows installation source files, and then replaces the incorrect file.