Problem with pfsense 1.2rc4 vpn and voip

[blueice]

Dear Sirs,
i have the pfsense 1.2rc4 installed in alix 2c3 with bios 0.99
I use the opt1 interface as primary wan. In this wan i have one ipsec vpn connection with other pfsense.
When i use this vpn for voip (sip) then when i answer the call pfsense make reboot.
If i config with just 1 wan and vpn in this wan it work fine.
I have the config attached.
It is a pfsense bug or i have a error in config?

Thanks
config.txt