Can't boot up after installing 10.4.10 + security update

Question

I got the automatic update yesterday (5/26) and installed the system & security updates onto my G5 as usual. Got the box that says to either shut down or restart. I clicked restart, and now all my computer will do is get to the blue screen that says loading OSX and then it stays on that forever. I've disconnected all peripherals, reset the pram -- no luck. Then I booted up from the disk tools CD and ran the permissions/repairs, but on all of them it stops about 3/4 of the way through the process and won't go any further. Out of desperation I even tried to do an archive/install and it wouldn't complete. My computer was working fine before this. Any suggestions would be MOST appreciated.
G5   Mac OS X (10.4.10)  

Answer 1

To emdh & the others:
If you hard drive has certain kinds of problems, they will be exacerbated by the updates (any updates, not just these). This can lead to an inability to restart.
These problems can be revealed by running Disk Utility's "Verify Disk" test (not the same as permissions repair). If that test shows any problems, you must restart from another disk with the OS & Disk Utility on it to repair them -- drives must be unmounted for this kind of repair to be made. Typically, people use the installer disk that came with their Mac for this.
Obviously, if your computer will not restart from an already damaged drive, you will have to restart from another one to perform the test or repair.
If the repair fails, you can try a more powerful disk repair utility like DiskWarrior, but some problems are too severe for any repair to succeed. In this case you must erase & reformat the drive, then reinstall the OS from scratch from your Tiger installer disk.
Since some disk problems are caused by failing hardware, it is a good idea to run the Verify Disk test again at this point. If your internal drive supports S.M.A.R.T. self-monitoring (& most do), you can check its status at the bottom of the Disk Utility window as another confirmation of your drive's health.
Assuming everything appears to be working correctly, you are now ready to perform any desired updates. Download a fresh copy of the Combo updater for your model (PPC or Intel) that takes you to the desired version number.
It is important not to install any third party software until this is done: anything that alters the basic operation of the OS can & usually will interfere with the update process, & since developers do not always make it evident their software does this (or sometimes claim incorrectly that it will have no effect), it is best to play it safe & avoid all of it until you can establish that the updated OS is working correctly. Add your third party stuff a little at a time, checking for proper operation after each addition. If you encounter any problems, consult the software's documentation for the best way to remove it, do so, & contact its maker to see if they have a later, compatible version.
Some users feel it is important to verify permissions before & after each install. I do not, but it can't hurt anything so do so if it makes you feel better.
There are other causes for updates to fail, but file system problems are among the most common, so the Verify Disk check is a good place to start.
Good luck!