To stop the Internet Security and Acceleration (ISA) Server service. open a CMD prompt and type:
net stop mspfltex
You will receive a message that informs you that the command can stop the other services that you installed during the ISA installation. Responding Y will stop the services. To restart them, you can restart the computer.
You can individually Stop / Start these services, using the long or short names:
"ISA Server Packet Filter Extension Driver" Mspfltex "Microsoft Web Proxy" W3proxy "Microsoft Firewall" Fwsrv "Microsoft ISA Server Control" Isactrl