Have you run a media check on the live cd or you can check the md5 sum from the terminal with the following command
md5sum /dev/cdrom
Md5Sum: e500113087c41ae772fead0e77e03b5b
There is no problem with the Gnome 2010.12 iso file.
Okay, I've check the md5 sum on the liveCD I used and it matches the one you have provided. Again, I am not sure why the KDE liveCD worked and the Gnome one did not. Both are 2010.12 versions. What I will do if I want to run Gnome is to install task-gnome and change the boot option.
Thanks again for your help.