I have two computers. On one computer the Ubuntu Live CD and a USB install key I created boot fine no problems, and have installed Linux on spare removable 120GB. But on another computer neither the CD or USB disc boot, it gets upto detecting network settings in Ubuntu and it just halts. Both machines have ATI videocards. I haven't tried resetting to BIOS defaults on the second PC, but I tried changing AHCI and standard IDE and that didn't help. I've also switched off the router/switch thinking some kind of DHCP issue. I just wish to boot off Ubuntu Live CD for emergency use.