cyrus spawniung lotsa processes

[RJ45]

Hello,
I have this problem with cyrus-imapd-2.0.16

last pid: 69049;  load averages:  0.16,  0.03,  0.01    up 1+19:22:04 08:36:18
1675 processes:1 running, 1674 sleeping
CPU states:  0.0% user,  0.0% nice,  0.6% system,  6.0% interrupt, 93.5%
idle Mem: 473M Active, 296M Inact, 199M Wired, 29M Cache, 112M Buf, 5544K Free 
Swap: 2048M Total, 2048M Free

1600 processes spawned by cyrus.
They are all of the type:

cyrus  69074  0.0  0.1  2576 1520  ??  Ds    8:39AM   0:00.01 deliver -e 
-m -- username

and imap does not work no more I have to restart cyrus.
anyone have some hint about this problem?
thanks

Rick