MacMini won't start-up properly after trying to update to OS10.5.7

Question

I am unable to hear the nice ping when I start my MacMini. I went to update from 10.5.6, and when the administrator box appeared, my administrator name was missing and my password didn't work ( but I did get the correct hint).
I have tried starting in the safe mode to change the password, but this didn't do anything. I tried starting from the start-up disk, ran utilities(can't run utilities with normal start-up due to needing password), found numerous errors and had them repaired. Ran a second time, and no errors were found.
At this point, I change my password back to the original password; and when I went to restart my computer, the nice ping was gone at start-up. I still had the same issue with my administrator name and password. Now though, even when trying to start with the "c" key pressed, I can't start-up using the disc.
I have tried loading onto an external hard drive and starting that way, with no luck as well. ALL important documents and files have been saved and removed, but I can't reload the operating system.
Who has the magic answer?

Answer 1

Hello
Usually this happens because of operating system file corruption from an improper shutdown. Your Macbook probably didn't enter safe-sleep when it ran out of battery.
You can probably fix your corrupt files by loading your OSX installation disk, and running disk utility.
Put your OSX disc into your macbook. If it doesn't boot into the disc, press down "Option" as you boot up.
Once the OSX installation process starts, keep clicking next/ok until you can see a menu bar on the top of the screen. Once you see the menu bar, click on it and select Disk Utility.
From there, you can check for errors and repair them.
When you're done, just select "shutdown" or "restart" from the menu. Don't proceed to re-install the OS!!
Good luck!