Any hint in /var/log/syslog or /var/log/apache2/error.log
Here's when I tried to reboot it and nothing happened:
Nov 19 21:20:01 pm01 /USR/SBIN/CRON[25452]: (root) CMD (/usr/share/vzctl/scripts/vpsreboot)
Nov 19 21:20:01 pm01 /USR/SBIN/CRON[25454]: (root) CMD (/usr/share/vzctl/scripts/vpsnetclean)
Nov 19 21:20:01 pm01 /USR/SBIN/CRON[25456]: (root) CMD (test -x /usr/lib/atsar/atsa1 && /usr/lib/atsar/atsa1)
Nov 19 21:25:01 pm01 /USR/SBIN/CRON[25516]: (root) CMD (/usr/share/vzctl/scripts/vpsreboot)
Nov 19 21:25:01 pm01 /USR/SBIN/CRON[25518]: (root) CMD (/usr/share/vzctl/scripts/vpsnetclean)
Nov 19 21:30:01 pm01 /USR/SBIN/CRON[25573]: (root) CMD (/usr/share/vzctl/scripts/vpsreboot)
Nov 19 21:30:01 pm01 /USR/SBIN/CRON[25575]: (root) CMD (/usr/share/vzctl/scripts/vpsnetclean)
Nov 19 21:30:01 pm01 /USR/SBIN/CRON[25577]: (root) CMD (test -x /usr/lib/atsar/atsa1 && /usr/lib/atsar/atsa1)
Nov 19 21:31:45 pm01 shutdown[25618]: shutting down for system reboot
Nov 19 21:31:45 pm01 init: Switching to runlevel: 6
Nov 19 21:31:48 pm01 rpc.statd[4074]: Caught signal 15, un-registering and exiting.
Nov 19 21:31:48 pm01 postfix/master[4556]: terminating on signal 15
Nov 19 21:31:58 pm01 shutdown[25890]: shutting down for system reboot
Nov 19 21:32:01 pm01 /usr/sbin/cron[5338]: (*system*vz) RELOAD (/etc/cron.d/vz)
Nov 19 21:40:01 pm01 /USR/SBIN/CRON[25957]: (root) CMD (test -x /usr/lib/atsar/atsa1 && /usr/lib/atsar/atsa1)
Nov 19 21:41:12 pm01 proxwww[26006]: Starting new child 26006
Nov 19 21:41:12 pm01 proxwww[26008]: Starting new child 26008
Nov 19 21:43:22 pm01 proxwww[26006]: login failure: 500 read timeout
Nov 19 21:47:38 pm01 proxwww[26062]: Starting new child 26062
Nov 19 21:49:41 pm01 proxwww[26006]: login failure: 500 read timeout
Nov 19 21:50:01 pm01 /USR/SBIN/CRON[26083]: (root) CMD (test -x /usr/lib/atsar/atsa1 && /usr/lib/atsar/atsa1)
Nov 19 22:00:01 pm01 /USR/SBIN/CRON[26167]: (root) CMD (test -x /usr/lib/atsar/atsa1 && /usr/lib/atsar/atsa1)
Nov 19 22:10:01 pm01 /USR/SBIN/CRON[26238]: (root) CMD (test -x /usr/lib/atsar/atsa1 && /usr/lib/atsar/atsa1)
Nov 19 22:17:01 pm01 /USR/SBIN/CRON[26301]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Nov 19 22:20:01 pm01 /USR/SBIN/CRON[26322]: (root) CMD (test -x /usr/lib/atsar/atsa1 && /usr/lib/atsar/atsa1)
Nov 19 22:30:01 pm01 /USR/SBIN/CRON[26395]: (root) CMD (test -x /usr/lib/atsar/atsa1 && /usr/lib/atsar/atsa1)
Nov 19 22:40:01 pm01 /USR/SBIN/CRON[26482]: (root) CMD (test -x /usr/lib/atsar/atsa1 && /usr/lib/atsar/atsa1)
Nov 19 22:50:01 pm01 /USR/SBIN/CRON[26578]: (root) CMD (test -x /usr/lib/atsar/atsa1 && /usr/lib/atsar/atsa1)
Nov 19 23:00:01 pm01 /USR/SBIN/CRON[26663]: (root) CMD (test -x /usr/lib/atsar/atsa1 && /usr/lib/atsar/atsa1)
Nov 19 23:10:01 pm01 /USR/SBIN/CRON[26748]: (root) CMD (test -x /usr/lib/atsar/atsa1 && /usr/lib/atsar/atsa1)
Nov 19 23:17:01 pm01 /USR/SBIN/CRON[26809]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)