Re: X Windows hard locks (requires hard restart) with nvidia drivers
Please note that a variety of problems can lead to the symptoms you describe, there is no single, easily isolated black screen of death bug, unfortunately.
@bobbyo: with X hung at startup, what does /proc/interrupts look like?
@haimeltj: can you still ping the machine when it hangs, can you login remotely? If so, does X consume similar amounts of CPU time on your system, when hung? If yes, please check /proc/interrupts, as well. Also, have you checked if X just takes very long to start, possibly several minutes?