Load balancer failover stopped working

[rlustemberg]

Hi All:
       I have a dual WAN setup, where the two wan interfaces receive IP addresses by dhcp.
I use WAN interface mainly for VOIP, with a failover gateway WAN2OPT
I use the OPT interface for all remaining traffic, with a failover gateway OPT2WAN
I also use a script to flush states after a failover event, following the advice in : http://forum.pfsense.org/index.php/topic,7808.15.html

I noticed this morning that the OPT had gone down last night at 23:00 approximately. Nevertheless failover had not kicked in and users could not browse the internet. I immediately reconfigured the rules not to use the load balancer, to be able to restore connectivity, with success.
The slbd logs had stopped a few days ago:
Apr 8 15:58:06 slbd[1998]: Service WANFAILOVEROPT changed status, reloading filter policy
Apr 8 15:58:06 slbd[1998]: ICMP poll succeeded for 195.151.xxx.xx, marking service UP
Apr 8 15:58:01 slbd[1998]: Service WANFAILOVEROPT changed status, reloading filter policy
Apr 8 15:58:01 slbd[1998]: ICMP poll failed for 195.151.xxx.xx, marking service DOWN

I open one of the pool configurations , saved it and applied changes, so as to quickly reload slbd, and the the expect behaviour occured. The OPT IP was marked as down. These are the logs:
Apr 14 09:51:58 slbd[54869]: ICMP poll failed for 217.19.xx.xxx, marking service DOWN
Apr 14 09:51:51 slbd[54869]: ICMP poll succeeded for 195.151.xxx.xx, marking service UP
Apr 14 09:51:51 slbd[54869]: ICMP poll succeeded for 195.151.xxx.xx, marking service UP
Apr 14 09:51:51 slbd[54869]: ICMP poll failed for 217.19.xx.xxx, marking service DOWN
Apr 14 09:51:45 slbd[54869]: VIP 127.0.0.1:666 added real service 195.151.xxx.xx:666
Apr 14 09:51:45 slbd[54869]: VIP 127.0.0.1:666 added real service 217.19.xx.xxx:666
Apr 14 09:51:45 slbd[54869]: VIP 127.0.0.1:666 sitedown at 127.0.0.1:666
Apr 14 09:51:45 slbd[54869]: VIP 127.0.0.1:666 configured as "127.0.0.1"
Apr 14 09:51:45 slbd[54869]: VIP 127.0.0.1:666 added real service 217.19.xx.xxx:666
Apr 14 09:51:45 slbd[54869]: VIP 127.0.0.1:666 added real service 195.151.xxx.xx:666
Apr 14 09:51:45 slbd[54869]: VIP 127.0.0.1:666 sitedown at 127.0.0.1:666
Apr 14 09:51:45 slbd[54869]: VIP 127.0.0.1:666 configured as "127.0.0.1"
Apr 14 09:51:45 slbd[54869]: Using configuration file /var/etc/slbd.conf
Apr 14 09:51:45 slbd[54869]: Using r_refresh of 5000 milliseconds

Now it does seem to be working, as it did when the box was setup a few weeks ago.
The only changes I made to the system since then is to reconfigure some IPSec tunnels.
Does anyone know where should I start looking to find out why slbd stopped working?

Any ideas?

[hoba]

What kernel are you running and is this a multiprocessor/core system?