Live CD won't boot on Lenovo ThinkPad E525
While I don't have the same laptop, I do have the same APU (A4-3300m | ATI Radeon HD 6480g).
I was having the same issue as you, but I was able to get Ubuntu 11.10 (fresh install) by doing the following:
1) Go here and download the alternate install liveCD: http://mirror.bytemark.co.uk/ubuntu-releases/oneiric/
2) Boot and install from the alternate LiveCD
3) After installation, boot with nomodeset
4) Drop into TTY, log in as usual
5) Install fglrx: sudo apt-get update && sudo apt-get install fglrx
6) After it's finished, just reboot and boot normally. You should be able to boot into Ubuntu 11.10.
Also, I should mention that everything will seem kind of sluggish. If you install compizconfig-settings-manager and turn off "Sync to Vblank" in General --> OpenGL, everything will be visibly faster and smoother.
I had similar problem. And I solved it like this:
re-boot without the LiveCD to your current Ubuntu version, refresh the configuration of Grub with this command
sudo update-grubthen boot with your LiveCD 11.10
From what I've understood, GRUB manages the way to start Ubuntu when several versions have been installed. The command sudo update-grub will clean it, that way your LiveCd won't have problem to run.