Amavis does not start sometimes

[bartounet16]

Good morning.
I just spent in my prod ZCS NE 6.07. The whole thing works rather well, but I have a problem ...

I reboot every night my services to my backup zimbra and sometimes amavis does not restart

The error message amavis is:

Aug 13 00:06:21 zimbraprod zimbramon[25334]: 25334:info: Starting antispam via zmcontrol
Aug 13 00:06:22 zimbraprod zmmailboxdmgr[30337]: wrote java pid 30337 to /opt/zimbra/log/zmmailboxd_java.pid
Aug 13 00:06:22 zimbraprod amavis[30374]: starting.  /opt/zimbra/amavisd/sbin/amavisd at zimbraprod.mouthiers.priv amavisd-new-2.6.4 (20090625), Unicode aware, LC_ALL="C", LANG="C"
Aug 13 00:06:22 zimbraprod amavis[30374]: user=1002, EUID: 1002 (1002);  group=, EGID: 1000 5 51 1000 (1000 5 51 1000)
Aug 13 00:06:22 zimbraprod amavis[30374]: Perl version               5.010000
Aug 13 00:06:23 zimbraprod amavis[30374]: SpamControl: init_pre_chroot on SpamAssassin done
Aug 13 00:06:23 zimbraprod amavis[30379]: Net::Server: Process Backgrounded
Aug 13 00:06:23 zimbraprod amavis[30379]: (!)Net::Server: 2010/08/13-00:06:23 Pid_file "/opt/zimbra/log/amavisd.pid" not created.\n\n  at line 318 in file /opt/zimbra/zimbramon/lib/Net/Server.pm
Aug 13 00:06:23 zimbraprod amavis[30379]: Net::Server: 2010/08/13-00:06:23 Server closing!

he seems unable to create it .pid.
Yet the permissions on the folder are correct ... more .. this is not systematic