radiusd service hang

Am running freeradius on a RHEL v3 box, to authenticate 802.11users against AD. All of sudden the 802.11 users cant get authenticated against AD, unless i reboot the radius service on linux box. It looks like radius service get hangs atleast weekly once for no reason, i couldnt find anything in the log file /var/log/messages. Is anyone facing this issue ? everytime when the user complain that wireless i not working, have to restart the service manually. any help would be appreciated.