Tariq Jaber

Some Secure Nat clients behind ISA server 2006 may face a problem browsing HTTPS websites and other websites that require login like http://mail.yahoo.com and http://hotmail.com. Monitoring a client facing this issue results in one or both of the following logs:
0×80074E24  FWX_E_CONNECTION_KILLED
0×0040017    FWX_E_TCP_NOT_SYN_Packet_Dropped

Such a problem can be solved by disabling “Web Proxy Filter” on the HTTPS traffic.
To do so:
Firewall Policy –> Toolbox >[Protocols] > right click the HTTPS protocol. In the Parameters tab, uncheck the Web Proxy Filter, since the HTTPS traffic is not cache.

For more information, refer to the KB article: http://support.microsoft.com/kb/944006