Hi, We have w2k with SP4,and ISA with SP1 is installed on it.Both web proxy and firewall service is working.Up to now there was no problem but today firewall clients cannot work.Firewall service seemed running and there was no event in the event viewer.After restarting the firewall service just a few minutes clients can work but then again they cant, in the clients firewall clint problem cant reach the isa. Than we found that one of our secure nat client machine (windows 98) makes the firewall service out of service.When this client establish firewall client session to ISA then firewall service becomes unavailable without any error message.Any idea about the problem ?