Amavisd spiking and mta not responding

[mailman.33]

I find this on my server.

scenario : Used to get frequent load spikes on server, and Amavisd is the top consumer. Sometimes mta hangs and postfix goes wild, message gets queued, eventually zmmtactl had to be restarted.
history : I am running 6.0.7, upgraded from 6.0.5
findings :

zmcontrol status shows all services running
antispam Running
antivirus Running
convertd Running
imapproxy Running
ldap Running
logger Running
mailbox Running
memcached Running
mta Running
snmp Running
spell Running
stats Running

Checked logs simultaneously when load spikes and i found this from clamd.log
-----------
-> /opt/zimbra/data/amavisd/tmp/amavis-20100921T094036-20936/parts/p002: Trojan.Agent-171592 FOUND
-> /opt/zimbra/data/amavisd/tmp/amavis-20100921T094036-20936/parts/p004: Trojan.Agent-171592 FOUND
-> /opt/zimbra/data/amavisd/tmp/amavis-20100921T093929-19186/parts/p002: Trojan.Downloader-97250 FOUND
-> /opt/zimbra/data/amavisd/tmp/amavis-20100921T094036-20936/parts/p002: Trojan.Downloader-97250 FOUND
----------

I further gave this and found amavisd, antivirus and mtaconfigctl not running .. ?? weird
Amavisd not working or what?
----
[root@server]# /opt/zimbra/bin/zmantivirusctl status
zmmtaconfigctl is not running
zmamavisdctl is not running
zmclamdctl is not running
[root@server ]#
----
or it shows only as zimbra user? su - zimbra?

I am begining to wonder if my installation was broken. Did i miss something? was amavisd and antivirus not installed? I had no info about it on zmsetup.log.

[mailman.33]

Can anyone tell me how amavisd works ?
what measures should we take when clamd.log shows trojan found? How does amavisd prevent it?

or normally is that an alert after precautionary measure from amavisd?

[mailman.33]

gave a start to anitvirusctl and antivirus, mtaconfig, amavis and clamd were indeed running. seems i got messed with running as root user.

I guess its part of zimbra quarantine process that clamd.log says trojan found. it reads from the db and after looking into zimbra.log, i can see those mails were discarded. But still thinking what could cause amavis to hang.

* Confirmed, some mails with virus alerts, delivered to the account. Antivirus is missing something.