Possible Solution for Hung RRAS Service
I've seen a number of posts in the VPN boards on the ISAserver.org message boards regarding site to site VPNs that stop working and the only way to get them up again is to restart the ISA Firewall machine. Attempts at restarting the RRAS service don't work.
The problem appears to not be a problem with the ISA Firewall itself, but with the RRAS Service on Windows Server 2003. You can check out this KB article and get a hotfix at: