date is stale on Server Status page with time when rsyslog restarted

[jackson]

# uname -a
Linux mail 2.6.26-2-amd64 #1 SMP Mon Jun 13 16:29:33 UTC 2011 x86_64 GNU/Linux

$ zmcontrol -v
Release 7.1.3_GA_3346.DEBIAN5_64 DEBIAN5_64 FOSS edition.

over half of year I fight with the status & stats problem (red crosses)/ A lot of topics at this forum describes problem, f.e. Server status data is not available, sometimes I won in this fight, after another Zimbra upgrade it's came back, but after upgrade to 7.1.3 it's gone. But.

Every morning I can see on Zimbra status page green signs with mark "date is stale" and graphs at Server Statistics page . Time always fixed 6:24 AM. At this time cron.dailly scripts starts.

# # ls /etc/cron.daily/
00logwatch  apache2  apt  aptitude  bsdmainutils  logrotate  man-db  mlocate  standard  sysstat

I think it should be linked to rsyslog restart:

# head /var/log/syslog
Nov  1 06:25:06 mail kernel: imklog 3.18.6, log source = /proc/kmsg started.
Nov  1 06:25:06 mail rsyslogd: [origin software="rsyslogd" swVersion="3.18.6" x-pid="28902" x-info="http://www.rsyslog.com"] restart

May be Zimbra loose link to some files, or keep wrong pid file. I don't know, but if I restart Zimbra, or launch /opt/zimbra/libexec/zmsyslogsetup script, all became to normal way -- status updates every 2 minutes, and graphs draws normally.

Any ideas, what I should fix? I can add to cron.daily zmsyslogsetup script, but I want find a source of problem.

[jackson]

also I find, that /var/log/mail.log is clean. That strange, because before update I have logs from Zimbra at both files -- zimbra.log and mail.log