[Brusco]

I bought an external Lacie DVD burner (firewire). No matter what I do it won't mount on my desktop. I tried other devices (Lacie firewire ext. HD) but I had the same problem. It seems my firewire ports had a problem. I then bought a firewire card and installed it in slot 5. It showed up in my system profiler (slot 5). But still after trying and trying I can't get the DVD drive to show up on my desktop. I downloaded and ran all the Lacie software updates, etc.

The reason I bought the drive in the first place was to install Tiger 10.4.6 (DVD). My system is now at OSX 10.3.9. My G4 is a Quicksilver 733Mhz

[Waragainstsleep]

Put the Tiger disc in, hook up the drive to firewire, then boot the Quicksilver with the Option (alt) key held down. This boots into the startup manager where you can choose which drive you boot from. You are looking for an optical disc icon labelled Mac OS X Install DVD. Click that then click the right arrow (Be patient its very slow on PPC Macs). If it boots, your firewire is fine, if you can't see the disc, you may have a blown bus. Try the onboard ports first.
Since you say the PCI card isn't working either, I suspect its just a corrupt firewire driver, but I have seen a blown firewire port cause other issues, and if the on-board bus is fried, it could be crashing the firewire driver as it loads. Not much you can do in that case besides replace your logic board.

If you have an external firewire hard drive, try that too. It may be possible that the optical drive and/or the PCI card do not support booting (unlikely though).

Check your on board ports for obstruction or damage, inside and out. If something is shorting a port out, this too may crash the drivers.

[rehoot]

A couple thoughts... maybe the disk is mounted but the icon is not showing on the desk top. Try double-clicking the icon for your computer from the Finder window. Another way is to open a Terminal window (Applications->Utilities) and type this:

ls -l /Volumes

(that's a letter L in the middle). If you see an entry for the external drive, then try using the "Go to Folder" comand from the "Go" menu in Finder.

Originally Posted by Waragainstsleep 

... You are looking for an optical disc icon labelled Mac OS X Install DVD. Click that then click the right arrow (Be patient its very slow on PPC Macs). drivers.

I'm not sure what this does, but if you are booting from the install disk, you could continue to boot from the OS X disk, then look through the menu bar and choose the option for "Run Disk Utility." If you booted with the external hard drive, you should see it on the left side of Disk Utility. If you don't see any disk, then maybe it is a bad bus as mentioned in the previous post. If you do see an icon, try to verify the disk or maybe reformat it (unless you have important info on that disk that is not saved elsewhere).

You could run Disk Utility without booting from the OS X disk, but there is a very tiny chance that booting from the OS X install disk would ensure that some software problem is not the culprate.