5/25/13 12:18:43.043 PM com.apple.launchd: (com.apple.xpchelper.F8010000-0000-0000-0000-000000000000) Exited with code: 1
5/25/13 12:18:43.063 PM xpchelper: getpwuid_r() failed for UID: 504, ret: 0, errno: 0
those messages filled up system.log. I could not open terminal or activitymonitor to try to kill opendirectoryd. After power off everything is back to normal. The root cause is unknown.