So at this point, I just want to get the operating system back, which was 10.3.9. So what can I do?

Have you tried resetting the nvram as Reboot suggested and at least tested your RAM sticks to the point of swapping them in one at a time? You seem reluctant to try the disk swap suggestion, and maybe you don't have ready access to another computer to do that.

XPostFacto changes something on the disk so it will boot from an OS X install disk that Apple says is not supported. People swear by it when it works; the rest swear at it. As Reboot said, there is a large section on troubleshooting on the XPostFacto support page. Many of the suggestions involve booting back into OS 9. Have you tried booting from your OS 9 or Mac OS X 10.3 install CDs by holding down the "C" key at startup? If that works, you might boot into OS 9 and try running XPostFacto to see if there is an Uninstall option in one of its menus. You might run Disk First Aid, and then try booting into the MAC OS X 10.3 install CD and run Disk Utility from that. Ultimately I think you need to do something that causes OS X to rewrite the boot block commands - did I hit that right, Reboot?

After doing that, you might try rebooting from the HD again. If it still doesn't work, I think you are ready for Michael's advice - reformat the drive and reinstall 10.3. If you have to reformat the drive, that would be the time to think about whether you still want to play around in OS 9 sometimes. You can create a small OS 9 standalone partition on your 60 GB HD. You can still install Classic on your 10.3 partition, or use the OS 9 partition for your Classic, but having a separate OS 9 partition would give you a place to start up from in an emergency like this, and it would allow you to set the extensions you want for standalone operation without having to change them to run Classic (if you have an alternative Classic installation on the OS X partition). I still have one on my OS 9-bootable G4 system from years ago, although I haven't booted into it for a long time, until last week to recall something for this thread. The whole OS 9 system, plus all the OS 9 applications that I was using when I transitioned to OS X easily fit onto a 3 - 4 GB partition, allowing "head-room" for virtual memory and data. (The actual footprint of the system plus all the applications is only 1.08 GB on the disk.)

Just some thoughts. Hope it helps.
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