I have a strange one. When I try to run various programs from the desktop, the start menu, or directly from program files, these programs' splash screens come up and then Windows Installer pops up, trying to install Microsoft Office 2003 Pro. When I cancel the install, the installer pops up again. This keeps happening until the main program windows display. I have uninstalled and reinstalled the programs, I’ve installed the latest version of Windows Installer, and I’ve cleared all my temp files. Windows Installer is set to run manually. I’ve done a deep scan and cleanup of the registry. I've done spyware and virus checks. Nothing changes. I'm running Windows XP MCE SP3. I'm not sure when the problem began. Microsoft Office 2003 Pro was installed successully years ago. Why does Windows Installer pop up?