I have downloaded F12 beta KDE LiveCD x86_64 and checked its SHA1 sum to be okay. I have then burned it onto a standard CD but it does not boot at all.
When I insert the disk and reset the laptop, it shows me the manufacturer's logo screen and the CD keeps spinning in the drive. I have tried changing sever BIOS options but to no avail.
I have to say that this laptop has 6 different linux distributions already installed, both i386 and x86_64 variety. The laptop hardware supportes 64-bit linux as I already have Ubuntu Karmic 64-bit going on it.
Sorry, since the CD refuses to go beyond the BIOS intro screen, I cannot post any more information.
I have also downloaded and burned the ISO multiple time just to be sure!