Ubuntu 12 crashed and took down network

Just had the exact same issue. All of a sudden most of my network went down. The only part still working was WiFi and I could only connect to the router, could not reach WAN and none of the wired LAN computers answered my pings. After rebooting the router several times to no avail I resorted to unplugging all ethernet cables. All of sudden it worked again, reconnected the cables and everything went down. After a bit of trial and error I found the culprit; my headless Ubuntu 12.04 server. I could kill the network by plugging it in and revive it by unhooking it. Eventually I resorted to pull the power. When it came back up it played nicely, I checked syslog and to my great surprise there was absolutely nothing there;

Sep 17 21:21:44 *** Normal event occuring
Sep 17 21:22:16 *** Normal event occuring
Sep 17 21:22:48 *** Normal event occuring
Sep 17 21:23:20 *** Normal event occuring
Sep 17 22:45:36 Atlas kernel: imklog 5.8.6, log source = /proc/kmsg started.
Sep 17 22:45:36 Atlas rsyslogd: [origin software="rsyslogd" swVersion="5.8.6" x-pid="1048" x-info="http://www.rsyslog.com"] start
Sep 17 22:45:36 Atlas rsyslogd: rsyslogd's groupid changed to 103
Sep 17 22:45:36 Atlas rsyslogd: rsyslogd's userid changed to 101

Strange indeed and kind of worrying. Not only did my server that has been stable since I first fired it up go down but it managed to bring the rest of the network with it.