Comment 4 for bug 712173

Hmm, usually if it was an X issue it would be immaterial whether plymouth is loaded or whether quiet/splash is on the boot prompt. That this issue only appears when plymouth is loaded seems to indicate that plymouth may be futzing up the GPU resulting in X failing when it tries to access it.

Please ssh into the box and reproduce the freeze, and then gather the output of dmesg as well as your /var/log/Xorg.0.log and /var/log/gdm/:0.log files while it is frozen, and attach those files here. These may have error message(s) that better pinpoint where the fault is occurring.