PM G4/667 doesn't boot after 10.4.11 update

Question

Hello,
We've got a Powermac G4/667 (Digital Audio, 384Mb RAM) equiped with a SATA card on a PCI slot, with 2 hard disks. On the biggest one (250 Gb, 60Gb free), we've got 17 users, as the mac is used as a backup server using AppleTalk under 10.4 (standard). Everything went fine until we updated to 10.4.11. After the update, the mac restarted with a question mark in a folder on the center of the monitor. After some though, it booted, but never actually managed to load the system (never ending gray apple on gray background).
Before bothering the community, I tried this :
• Single user boot : same result (no access to the text interface)
• Installed the 10.4 on the other disk, booted fine, updated to 10.4.11, boots fine. The 250Gb mounts fine. Run (repeatedly) Disk Utility and even fsck from the Terminal on the 250Gb disk. Both say everything is ok.
• Boot pressing the alt key : the mac (after very long thinking) only shows the second disk (now with 10.4.11)
• When booted from the second disk, used the System Preference panel Starting Disk to ask a boot from OSX system folder on the 250Gb disk (shown in the list) : no boot (boot back to the second disk)
• When booted from the second disk, used the System Preference panel "Startup Disk" (excuse my English, using a French system) to ask a boot from the Mac OS 9 system folder on the 250Gb disk using : no boot (boot back to the second disk)
• Tried to exchange the connections of both disks to the PCI SATA card : no success, still booting on the second (now first) disk.
From all that, I believe that :
• It's not the OSX system folder that's altered (otherwise OS9 would have booted)
• It should not be the SATA card connextion, as the last experiments shows.
• It's quite strange to see the system folders of the disk in the system prefs boot list and not in the boot list when pressing the Option key at startup
• Someone told me there might be a "boot sector" that's damaged (sounds like PC stuff to me).
OK, I know I could format the drive and reinstal OSX, my 17 users by hand, but then I'll have to ask them a full backup (opposed to the incremental they do daily) and it would take VERY long.
Any hint someone ?
If nobody can help recovering this disk as a start up disk, my only alternative now is to buy another disk, type my 17 users in, and try to copy their data from the 250Gb.
But what about the data rights?
Thanks,
Message was edited by: Sylvain M

Answer 1

John,
I never heard of such a thing either, but there must be a way for the disk to boot, no?
About the suggestion to reinstal the system, thank you, but I don't want to loose the 17 users and their data. I tried and the installer would not take them back, stating that a more recent version of OSX (10.4.11 instead of 10.4.0 on the CD, I suppose) was installed.