Guys the DVD drive works fine with movies and so on.

It is giving me hard time only with booting, as I said not only with Leopard but also with Disc Warrior. No one of them boots.

I tried to hold Option while reebooting and I choose Leopard DVD for the reboot. It accept it but then the DVD start to do weird noises and I had to turn the power off as nothing was happening...

I don't have external DVD drives to connect via firewire but have 2 external HDs... Is ti ok?

It would be okay if you were able to read from the Leopard DVD, create or wipe an existing volume (partition), create a disk image of the Leopard DVD and restore to that internal (new/blank) volume, then boot from the volume and install to your current Tiger installation.

Hope that made sense. Otherwise, read it again slowly

That would work.

Or restore to an external (bootable!) hard drive, such as iPod, or USB HDD (FireWire, I suppose, since it is a G4 and G4's can't boot from USB in my experience, only FireWire iPods and similar).

You have to try booting off another device. Huy has the right idea.

Just for rough instructions for another method if you can't follow Huys, see below:

Since you have limited external devices to try from, I read your girlfriend has an imac as well. You can boot yours into target disk mode, plug into hers via firewire and your HD will show up on her desktop, throw the leopard dvd into her machine, run the installer and install leopard to your HD. Good luck.

Just did a new test....

The CD of Discwarrior reboots without problems....

So now is only the DVD of Leopard that doesn't.

What could be the cause?

The DVD drive can read the DVD and I can browse through it but simply won't reboot for the reasons I told you...

Thanks for the suggestions guys but why doesn't want to reboot?

Yes my girldfriend has a new 24" iMac but we don't live together...

Probably I should call Apple or go to an Apple centre.

Could it be because the DVD is a double layer?

A temperamental DVD Drive. They get old and do funny things before they die. Just like humans.

Seriously if you've had this much trouble jsut trying to boot from either bootable disks, your drive is on its way out. Do one of the above two suggestions, or if you really don't want to, then get a replacement Leopard dvd from apple on the odd chance it's faulty (but would test it in your g'friends computer first) and try again.

Maybe the drive can't read dual layer disks?

My DVD driver can't read dual layer discs for sure! Is an iMac G4, a bit more than 4 years old... But if I put the DVD it sees it and I can read the PDF files in it. Only it won't work if rebooting... Maybe that's the problem!
Hey why whasn't that written when I bought the DVD from the Apple Store?

Do you have any other dual layer discs to test with?
I don't think it should be an issue really, if you have a Combo or SuperDrive, that can read DVDs, single and dual layer.

Your machine meets the system requirements as stated by Apple (fast CPU, G4, DVD ROM, HDD etc) and so it should be no problem to install Leopard.

You might have a dodgy Leopard disc as mentioned, so maybe go down that avenue.

Since you're able to read from the disc, but simply cannot boot from it, why don't you just try to make a disk image of Leopard and restore to a partition (got a spare iPod?).

Yes, it could be a dodgy disc then... uff... can it be replaced by Apple simply calling them?

No idea haven't had to use them before.

I'm guessing you'll have to send in your discs for an exchange? Call up Apple and see what they can do for you. Or, it's a perfectly good disc and there's something wrong with your machine...

Antonio: there have been a few other reports where the retail 10.5 disc exhibits read errors, even the same physical disc across more than one machine, which leads me to believe that your disc is one of the small number which was a slightly borked pressing ... in this case, you should be able to ask your place of purchase for a fresh copy of the disc.

HOWEVER! The fact that you can sort-of read it, and have had problems reading some other discs, I'm with HDriveKilla -- your optical drive has either dirty lenses, an alignment problem with the optical pickups, the lubricant on the tracking-screw (that moves the heads back and forth) is starting to dry up, or some other age-induced quirk that means your DVD drive is on its last legs.

Get one of those CD/DVD Lens Cleaner discs with the little tufts of carbon-fibre brushes glued to the underside (they're only a few dollars from many places, including the media/stationary section of your local Woolworths supermarket for example) and run it through two or three times, then try and boot your 10.5 disc again. If that doesn't seem to help, replace the DVD as mentioned above, and try again. If the replacement copy still gives you problems, then your only recourse is to replace the optical drive in your iMac G4.


Brains

If it couldnt read Dual-Layer DVDs, you'd have trouble with most Commercial DVDs too!

Thanks guys! I do what you all suggested me.

One thing is not clear thought... don't double-layer DVDs can only be read by specific DVD drivers? My iMac is more than 4 years old, yes it has Superdrive but double layers DVD are a new technology, aren't they? Isn't the blue laser technology? Or I'm just confusing technologies?

Is only a bit more than 4 years old! How can it be?

Is there anything I can do to re-allign the optical pick-ups or other things via software or anything else? Maybe open the MAc and clean it?