Nick (others too), If you'd like to test a workaround I've developed that should allow you to function without disabling SACK on Microsoft Windows, please download this version of IPFilter and test it:
http://coombs.anu.edu.au/~avalon/ip_fil4.1next.tar.gz I've made it specifically match a packet exactly to the right of the allowed window if SACK is in operation. I've also fixed another "OOW" related bug where a window sacle of "0" would cause window scaling to be disabled in window size calculations for both ends. Darren
