Suddenly load average of 15-18???

[Thomas Cameron]

All -

spamc is suddenly bringing my mail server to its knees.

Running RHEL 4 with the spamassassin-3.0.1-0.EL4 (supplied by Red Hat) and 
spamass-milter-0.3.0-3 (I made that RPM) along with razor-agents-2.67-0, 
dcc-1.3.0-0 and pyzor-0.4.0-0.

All of a sudden about two days ago spamc processes were chewing up the 
machine - sendmail was actually rejecting messages because the load average 
was so high!  This is a machine that is only used for about 6 users...  It 
only handles around a thousand to two thousand messages a day.  I am the 
only admin on it and nothing has changed.

Here is my local.cf:

--- begin ---
required_score 5
report_safe 1
rewrite_header subject **SPAM** _SCORE_
ok_languages en
ok_locales en
use_dcc 1
use_pyzor 1
use_razor2 1
whitelist_from_rcvd address@hidden
whitelist_from_rcvd address@hidden

score ALL_TRUSTED 0 0 0 0
--- end ---

Here are the relevant lines from my sendmail.mc:

--- begin ---
INPUT_MAIL_FILTER(`greylist',`S=local:/var/milter-greylist/milter-greylist.sock')dnl
define(`confMILTER_MACROS_HELO', `{verify}, {cert_subject}')dnl
define(`confMILTER_MACROS_ENVFROM', `i, {auth_authen}')dnl

INPUT_MAIL_FILTER(`spamassassin', `S=local:/var/run/spamass.sock, F=, 
T=C:15m;S:4m;R:4m;E:10m')dnl
define(`confMILTER_MACROS_CONNECT',`b, j, _, {daemon_name}, {if_name}, 
{if_addr}')dnl

INPUT_MAIL_FILTER(`clamav-milter', 
`S=local:/var/run/clamav/clamav-milter.sock, F=T,T=S:4m;R:4m;E:10m')

--- end ---

I have no idea why it is doing this...  It was working fine and then this 
happened sort of out of the blue.  Any pointers?

Thanks!
Thomas