Can't boot Fedora 17 after software update

[idk666]

Following installing the latest software updates for Fedora 17, after rebooting I can't get to the login screen. I get a far as the "fireworks" background image appearing and then for a split second it flashes to a black background with:

[OK] Started WPA Supplicant daemon.
[OK] Started Sendmail Mail Transport Agent.
Started Sendmail Mail Transport Client...
[OK

and then it goes back to the fireworks process and cycles constantly back and forth between the screens without getting to the login screen.

It's so fast I had to take a video with my phone and slow it way down in WMP to get a screenshot (attached).

I'm completely stumped, any ideas would be greatly appreciated !

Thanks !

[george_toolan]

See http://forums.fedoraforum.org/showthread.php?t=281237

[idk666]

Thanks very much George !