Mac won't start up

Powermac G5 Dual 2GHz

Using the software update I was upgrading from 10.4.8 to 10.4.9 amongst other things the software update suggested. All seemed well until the 10.4.9 bit, mid way it stopped, saying there was a problem.

Ever since I cannot get the mac to start up. The white screen with apple logo and circling countdown appears, it gets to the blue screen, the window with the apple logo and "Mac OS X" appears but no blue line appears and the mac come sto life with the desktop rebuilding.

I've used the install disc, done disk utility, first time repaired some "illegal name" problems and ever since it says the drive appears fine. but Still no startup.

What is wrong here? How do I fix it?

Cheers
neye:

I read about this recently from an article MacHeadCase (so full credit to MHC - it was a great find and I'd say ALL mac users should check it out) sent me after a little problem I had. Have a read of this. It should help explain a lot. The article suggests attempting to boot or reinstall in Target Disk Mode (you could probably find info on that on the apple site or just through google) in the case OS X doesn't boot.

I actually had to reinstall OS X for my problem, as nothing else seemed to work. So, I backed up most of my stuff and reluctantly popped the install disc in. My problem wasn't as serious as yours (most applications wouldn't accept my admin password for updates and certain tasks) but this fixed the problem perfectly.

If you've access to the resources for this, it might be your best bet. I'm sure others will be able to guide you a little better than this, perhaps recommend something better even. I hope you get it sorted - it's a scary thing when your mac doesn't work like it should.