Hang on reboot with Fedora 19 (after software upgrades)

[Florian Weimer]

I tried to reboot after some software upgrades (which were released
during the last few days). The system switched to a text console,
showing a stray boot message, "[ OK ] Started Postfix Mail Transport
Agent.", but did not proceed with the reboot.

Is there something I can do to debug this?  Should I boot from a
rescue system and save some log files?  (The system is currently still
stuck, but I doubt there are any magic keys to unlock it.)