On Fri, 9 Jun 2006, Ben Hoefer wrote:

"[..]   
  Yesterday I tried to compile my 1st ADA programm "Hello World!". Unfortunately, I got the following error message:
  
    gnatmake -PC:/GNAT/bin/helloworld.gpr helloworld.adb -d 
    fatal error, run-time library not installed correctly
    cannot locate file system.ads
    gnatmake: *** make failed.
   
      process exited with status 4
  
Well, when I installed GNAT / GPS I affirmed the options suggested by the programm (for instance the folders ...) So, if the run-time library is not installed correctly - I can't help it: GNAT / GPS did install this library!
   
  I deinstalled GNAT / GSP, and I installed it again. I tried to compile my little program again. And I got the same error message.
   
  So, what can I do to make this strange GNAT / GPS compiler work?
   
  I would appreciate any hints, suggestions and recomendations."

I suspect that what is needed has been installed but that a 
poor setup is hindering easily sompiling. Please search for the file
system.ads and report to us its full path. After finding it, please type 
the command
set
in the DOS command box in which you would invoke gnatmake and send a copy 
of the output (environment variables' settings) so that we could suggest 
modifications such as adding the path you found to GCC's (and hence 
GNAT's) include (cf. specification) path enviornment variable CPATH (which 
is not restricted to C).