I too have this problem. The CD is set at the top of the boot list. When attempting to boot the rescue disk it just has a blinking cursor. I decided to have a play, so I burnt the CD image as it is originally downloaded (pre update). This boots successfully, so I'm assuming that whatever process is updating the ISO image with the updated virus definitions is stuffing the boot part of the ISO. Obviously this isnt happening for everyone so clearly there's something environmental going on here, but I'm also obviously not the only one affected by this. For what it's worth I'm running Win 7 64bit.