G4 no DVD read?

I have a G4 with 1.25GB of ram recently installed (new 1GB board). I am trying to update to Leopard. The drive does not seem to recognize DVD's. I can play CD's, I used to be able to watch DVD's. But now even the kid's hunky and spunky Cartoon DVD will not play. I tried loading my original disk for software install and it seemed to load OK. It even had a little DVD on the disc icon.
Any ideas? The final goal is to be able to load tunes into my daughters ipod.

if the dvd drive is playing up then maybe consider a replacement drive

Is it a G4 tower, if so the pioneers are very inexpensive replacements and support dual layer DVDs

Pioneer DVR-116D-BK [Black Bezel] 'SuperDr... (DVR-115D-BK) at OWC

Thanks for the reply louis. It is the "gumdrop" style MAC. I was hoping thjere was some sort of software error. We really only need to install the Leopard software as I don't watch movies on it.. The computer still reads CD's just fine. Would the external drive you mentioned work for me?

I second Louishen's advice. The 116D is the latest ATA optical drive from Pioneer. I've very recently bought a 115D, and it works flawlessly in an external enclosure. You could put a 116D directly into your G4 but a firmware update *may* be necessary.

Looking at the link above, I have a couple questions.
Where is the power for this device coming from?
How does it feed into my computer? USB?
How do I load software to run it into my computer?
If the above above are non issues, heck for $30 I will go for it!

Look at an internal replacement. A USB2 device will not be bootable on a G4, you need Firewire. Internal replacements are quite simple, the power comes from the cable connection.

Is the G4 867MHz or faster as that is the minimum for Leopard?

Here is a video link showing how easy this job is. Only difficult part is removing the power cables - struth they are tight:-

Tech Center at OtherWorldComputing.com

proc Speed is 1.25GHZ. I have reloaded the software that came with the machine. No luck. I was then downloading some DVD player type software updates from the Apple website and left the room. When I came back the kids cartoon DVD was playing on my computer! I then restarted the machine and have not been able to play a DVD since. However the iMAC software install DVD comes up on the screen with a little DVD logo in it. Very mysterious! I don't mind doing a little surgery, but, I wonder if I jazzed up the software in my machine?