First, about FSUIPC, we don't need, we don't use, and we are not affected by the presence/absence of FSUIPC so, this certainly wasn't the source of the problem.
However, FSUIPC works with all releases of Simconnect, our Addon Manager works ONLY with the SP2 or the Accelleration version. So, the fact the FSUIPC is running, doesn't necessarily means the Simconnect subsystem works. Simconnect, being a Side-by-side dll, is installed in multiple versions so, if you installed FSX, then SP1, then SP2, then Acceleration Pack, you have all 4 Simconnect releases installed, and they can even run at the same time so, if there's a problem with the SP2 or the Acceleration version, you might still have addons that are compatibile with older version that works, with addons that require the new version that don't.
You can try to activate the Simconnect diagnostic mode:
Open notepad, and copy the following text:
Code:
[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.