I think I found the problem. (OpenVZ client)
Jail kit gives this error when I try to upgrade it.
Setting up jailkit (2.14-1) ...
insserv: warning: script 'K01jailkit' missing LSB tags and overrides
insserv: warning: script is corrupt or invalid: /etc/init.d/../rc6.d/S00vzreboot
This probably messes up the users cron.