01. If 'System Profiler' was relocated from its original '/Applications/Utilities/' folder - the 'More Info...' button of the 'About This Mac' window, would still function correctly (that is, the button would still be enabled, and properly launch 'System Profiler'.).
02. It is very important to identify the specific version of MacOS X installed, when posting a problem / request. Re-installing an application - from a 'Mac OS X install' disc (CD / DVD), via 'Pacifist' or other means (such as via 'Terminal's command-line) may not install all necessary components associated with said application. Sometimes, one may have to reinstall an application via a 'MacOSXUpdCombo...' (or equivalent) file - to obtain a copy of the version earlier removed.
An example:
The 'Tiger' 'Mac OS X Install DVD' installs 'System Profiler' version 4.1. The 'MacOSXUpdCombo10.4.9PPC' file installs 'System Profiler' version 4.1.1.
03. Most 'Mac OS X Install' discs contain an '/Applications/Utilites/' folder. In it will be (some version of) 'System Profiler'. Insert (only; do not boot from) the 'Mac OS X Install' disc and from the 'Apple' menu select the 'About This Mac' menu item. The resultant 'About This Mac' windows' 'More Info...' button should be enabled; click on it. If 'System Profiler' is launched (opened, run), and appears to function correctly, then consider dragging 'System Profiler' from the CD / DVD (in the discs' '/Applications/Utilites/' folder) to the Macs' hard disk drives' '/Applications/Utilities/' folder.