Windows 2003 Firewall and ipnat.sys

When trying to start the Windows 2003 firewall I get: “Windows Firewall can not run because another program or service is running that might use the Network Address Translation component (IPNat.sys)”

The server is unreachable by rdp or ping with the firewall off. This is Windows 2003 Standard SP2 and has RRAS disabled.

I can stop/disable ipnat in the device manager and the server is accessible, but then obviously the windows firewall doesn’t work.

I’ve tried using sysinternals handles program but it doesn’t find anything using ipnat.sys when I have ipnat running.

Anyone have any suggestions on something else I can try?