A lot of it depends on what you are connecting to, like XP or Vista and what version of Activesync, etc. I connect to AS 4.1 and XP and my Advanced Networking is checked. I have had no issues with AS.

The default setting for Advanced Networking is checked. Possibly when you did you master reset (hard reset), was when it was set to checked.

Sorry for your frustration. Glad you got it working.

Rob.