10.5.8 Combo Update Issue

Hello there! I'm afraid I need a bit of help with a problem I've been having for a few days. I've been running OSX 10.5.1 for a while, and just recently upgraded to 10.5.2, thinking I had to update through every OS upgrade there was. You can imagine how relieved I was to see the 10.5.8 Combo pack! I downloaded it through software update, and then tried installing it twice, but each time it gets about a quarter of the way through installing and then shuts down, with an error message that says "The installer could not validate the contents of the 'MacOXSUpdCombo10.5.8' package. Contact the software manufacturer for assistance." I verified and repaired disk permissions a few times, so I don't think that's the problem, tried the all powerful 'restart and pray' method, and downloaded it through safari, to which I got a invalid checksum on mounting the dmg. I haven't had any other problems recently on this computer, just this (which is kind of a miracle).

Anyone know what's going on?

Welcome to Mac-Forums Jennuxia

Sounds like the download got corrupted somewhere along the process. Try donwloading it from the link below instead, the link for the update download is near the bottom just under the Related Links heading.
Download Apple Mac OS X for Mac - The latest OS from Apple. MacUpdate.com

Hope this helps

- Simon

Okay, I tried downloading that one, and didn't start and stop the download at all, but this time it says "codec overrun" when I try and mount the disc image.

EDIT: tried it again and now it's back to invalid checksum.

You need to repair your hard drive - Not the same as repairing permissions:
Resolve startup issues and perform disk maintenance with Disk Utility and fsck

If this doesn't help, there's a good possibility you have a hardware problem - RAM most likely, motherboard and hard drive also possible.