Since you have McAfee, and McAfee doesn't allow to exclude specific files from scanning (unless you have the Enterprise version), you can't have followed the suggestion in that thread entirely, which also asks to exclude our two executables from scanning before launching FSX.
Try doing it again, after a Windows reboot, with the Antivirus *entirely* turned off, even when launching FSX.
If you it still doens't work, you can try to activate the Simconnect diagnostic mode, this way:
Open notepad, and copy the following text:
[SimConnect]
level=verbose
console=1
RedirectStdOutToConsole=1
OutputDebugString=1
; file=c:\simconnect%03u.log
; file_next_index=0
; file_max_index=9
Save the file as SIMCONNECT.INI in this folder:
Documents And Settings\YOUR LOGIN NAME\Documents\Microsoft Flight Simulator X Files
At the next FSX launch, you should see a text window with diagnostic message, that should tell you what's going wrong. Let me know what you are getting, so we can have an idea what's happening.