Exim dead but pid file still exists

[hehachris]

exim never start now! (just installed clamav and it worked fine, but suddenly failed)
this is a FC2 box with DA installed

i have done the following to check is it caused by permission
but the result seems to tell me it is not =(

any suggestion?

[root@server1 var]# grep ^mail /etc/passwd | cut -f1,3-4 -d:
mail:8:12
mailnull:47:47
[root@server1 var]# touch /var/log/exim/testlog
[root@server1 var]# ls -lad /var/log
drwxr-xr-x 12 root root 4096 8??24 08:03 /var/log
[root@server1 var]# ls -lad /var/log/exim
drw-rw-rw- 2 mail mail 4096 8??24 08:27 /var/log/exim
[root@server1 var]# ls -l /var/log/exim
total 9860
-rw-rw-rw- 1 mail mail 352866 8??24 07:17 mainlog
-rw-rw-rw- 1 mail mail 660373 8??21 04:02 mainlog.1
-rw-rw-rw- 1 mail mail 5960015 8??14 04:02 mainlog.2
-rw-rw-rw- 1 mail mail 2169709 8?? 7 04:02 mainlog.3
-rw-rw-rw- 1 mail mail 689573 7??31 04:02 mainlog.4
-rw-rw-rw- 1 mail mail 31321 8??24 06:59 paniclog
-rw-rw-rw- 1 mail mail 3328 8??21 04:02 paniclog.1
-rw-rw-rw- 1 mail mail 2912 8??14 04:02 paniclog.2
-rw-rw-rw- 1 mail mail 2912 8?? 7 04:02 paniclog.3
-rw-rw-rw- 1 mail mail 2912 7??31 04:02 paniclog.4
-rw-rw-rw- 1 mail mail 0 8??24 02:10 processlog
-rw-rw-rw- 1 mail mail 0 8??14 04:02 processlog.1
-rw-rw-rw- 1 mail mail 0 8?? 7 04:02 processlog.2
-rw-rw-rw- 1 mail mail 0 7??31 04:02 processlog.3
-rw-rw-rw- 1 mail mail 0 7??24 04:02 processlog.4
-rw-rw-rw- 1 mail mail 42357 8??24 06:57 rejectlog
-rw-rw-rw- 1 mail mail 51331 8??21 03:10 rejectlog.1
-rw-rw-rw- 1 mail mail 24648 8??14 03:41 rejectlog.2
-rw-rw-rw- 1 mail mail 18862 8?? 6 21:49 rejectlog.3
-rw-rw-rw- 1 mail mail 17413 7??31 01:57 rejectlog.4
-rw-r--r-- 1 root root 0 8??24 08:27 testlog

 

[hehachris]

i have even done:
# ps waux | grep directadmin
root 9490 0.0 0.0 4632 588 pts/0 S 08:40 0:00 grep exim (no this process @@)
# rm /var/run/exim.pid
# service exim restart

it can start for a second, but then stop itself

 

[hehachris]

now exim can be started..
but it looks like hang with each process...
eg: pid 13064 appear for a long time, i kill it manaully and kill the exim.pid...then restart exim. however, exim will hang with another pid @@
cannot receive/send email for a whole day>"<