On Additional CDs screen, click on Additional CDs Install with no CD in drive.
Firstboot will crash.
I could reproduce this bug too.
Firstboot will crash and leave the message ""putfont : pio_font" on ctrl-alt-f7.
Only by rebooting and doing the firstboot procedure again Phoebe starts in X.
I tracked this down to a pygtk2 bug when using GtkInvisible. pygtk2-1.99.14-1
should fix the problem, as katzj pointed out.
*** Bug 81548 has been marked as a duplicate of this bug. ***