Re: 185.18.08 randomly crashes (8600GS, X86_64)
This is the exact same issue that I have been having with my 8400M GS under X86_64, but it happens on my machine with all 180* and 185* drivers. I see nothing of interest related to the issue in my logs other than the same error you posted that indicates that xorg crashed.
There seems to be no pattern to when xorg crashes, it usually seems to happen when the I'm not actively using the machine or running anything specific apart from possibly pidgin, firefox and applets and processes running under Gnome. I've also had the phenomenon occur as I was watching or doing something like refreshing a page in firefox, but there's nothing to indicate a specific correlation with anything. I also haven't noticed a specific period of time that passes before the crashing, it's happened within a few minutes of starting xorg up to as much as 36 hours after starting, but it generally seems to happen within 12 hours.
I've currently reverted back to 177.82 (and have no problems), but I've attached a slightly older log from when I tested 180.29 to this post and another from my current setup.