I see this problem doesn't appear to be solved quite yet; I'm having a vaguely similar issue with a 13.10 (Server, x86) install on an ASUS EeePC 900 that I do-release-upgraded to from 12.04. I'm running Slim and Openbox, both of which worked normally on 12.04, 12.10, and 13.04. Similar to what someone posted on the first page of this thread, if I log in to a console and restart slim, everything comes up normally. The sleep and restart workaround in rc.local didn't work for me. I haven't tried switching display/login managers yet, but I'd like to stick with the current setup, if possible.

My Xorg.0.log file: http://paste.ubuntu.com/6520891/