Hey there,
I've been trying to install kubuntu 13.04 from the live cd with no success at all. It crashes at 80% or even less. I have an internet connection working.
So let me guide you about what is happening right now.
1. when I attempt to use the regular live on the boot screen: nothing just black screen with these two sentences
Starting network mount filesystems
stopping network mount filesystems

2. so after lot of time trying to get into the desktop...I give up and reboot the machine...everything is as always (wrong I mean)

After some workaround and thanks to Macmichigan. I'm doing this now.

1. type live video=offbff nouveau.modeset=0 single at boot screen

2. screen frozen when the card is detected and I type with extreme care this:
modprobe nvidiafb mode_option=1680x1050-32 which is my monitor resolution (mac cinema 20")

3. after I'm on the terminal and I type: start lightdm

After that miraculously I'm at the enter screen and I went finally to the desktop, but when I try to install the program onto my 150gb hd formatted free space...the installer crashes at 80% and tells nothing.
Also rekong crashes all the time

IS THAT A BUG?
If so please tell me how can I fix this....no clues at all. I'm a very newbie, no programmer at all.

Thanks.

My mac is a g5 dual 2GHZ nvidia geforce 6600 with 1gb memory.