Desperate for Lubuntu 12.04 on my old Powermac G4 but will not load!

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http://ubuntuforums.org – Hi, I have a powermac G4 Quicksilver 733GMhz but cannot get the Lubuntu alternate PPC iso to install, it simply spits the cd out. The video card is an Nvidia NV11 ( Geforce2 MX/MX 400). It has over 1.12gb ram installed. I have only managed so far to load and run mintppc on this machine which is ok but it certainly is NOT Lubuntu 12.04 which is perfect on my Imac g4 ;-) Any help or advice much apreciated. (Hardware)