If, as you say, the problem continues after a reinstall of the system software, then the problem is not a software one. A re-install should be considered the last resort in the troubleshooting chain, one that is performed after exhausting all the other methods of repair. For instance, did you ever repair the Disk Permissions? The symptoms you describe can sometimes be fixed by running this utility.
Run it now and see if it makes any difference. Let us know
As an absolute last resort, you can Format and Install the OS from the restore CD's that came with the G5. Be aware though, this method WILL destroy ALL your data.
Suddenly many of my Mac applications will not start up. Mail, Safari, many preferences, and Mac Help are some examples. I click on the application but it never boots up. This happened once before about 6 months ago. I reinstalled my system software and the problem was fixed. I did the same thing this time but the problem remained.
I'm on a Power Mac G5, OS version10.3 (I was at version 10.3.9 before I reinstalled the system).
Now that I've reinstalled the original system software (10.3), I can't upgrade to newer versions. The Mac software updater also is not working.
Any suggestions would be great!