现象：开机或登录，UserEventAgent占用CPU 100%，内存占用每秒疯狂增长，曾经达到过20G被Force Quit
可重现：100%重现
解决方法：开机执行如下shell脚本，并输入密码
bugpid=`ps -ef |grep UserEventAgent |grep System |awk '{print $2}'`
echo 'UserEventAgent (System) pid was '$bugpid
sleep 2
sudo kill -9 $bugpid
sleep 1
bugpid=`ps -ef |grep UserEventAgent |grep System |awk '{print $2}'`
echo 'UserEventAgent (System) pid is '$bugpid以下是相同案例，但通过禁止某些系统启动项 来解决的
https://discussions.apple.com/message/26003314#message26003314
http://forums.macrumors.com/threads/usereventagent-using-114-cpu.1741322/
http://apple.stackexchange.com/questions/221091/what-causes-the-usereventagent-to-run-with-100-cpu-usage
