現象：開機或登錄，UserEventAgent佔用CPU 100%，內存佔用每秒瘋狂增長，曾經達到過20G被Force Quit
可重現：100%重現
解決方法：開機執行如下shell腳本，並輸入密碼
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，但通過禁止某些系統啓動項 來解決的
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