After a second attempt at reinstalling FSUIPC with the original DLL.XML renamed, I do have the add-ons menu in FSX. The first time I tried FSX ended up not responding after a few minutes. My computer just decided to act up, I guess. But with my original DLL.XML renamed, the add-ons menu item is there.
I fixed the DLL.XML lines as you suggested and here they are again, just to make sure everything is OK there now:
<?xml version="1.0" encoding="Windows-1252"?>
<SimBase.Document Type="Launch" version="1,0">
<Descr>Launch</Descr>
<Filename>dll.xml</Filename>
<Disabled>False</Disabled>
<Launch.ManualLoad>False</Launch.ManualLoad>
<Launch.Addon>
<Name>Addon Manager</Name>
<Disabled>False</Disabled>
<ManualLoad>False</ManualLoad>
<Path>bglmanx.dll</Path>
<Launch.Addon>
<Name>Object Placement Tool</Name>
<Disabled>True</Disabled>
<ManualLoad>False</ManualLoad>
<Path>..\Microsoft Flight Simulator X SDK\SDK\Mission Creation Kit\object_placement.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>AbacusCatapult</Name>
<Disabled>False</Disabled>
<Path>AbacusCatapultFSX.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>Traffic Toolbox</Name>
<Disabled>True</Disabled>
<ManualLoad>False</ManualLoad>
<Path>..\Microsoft Flight Simulator X SDK\SDK\Environment Kit\Traffic Toolbox SDK\traffictoolbox.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>Visual Effects Tool</Name>
<Disabled>True</Disabled>
<ManualLoad>False</ManualLoad>
<Path>..\Microsoft Flight Simulator X SDK\SDK\Environment Kit\Special Effects SDK\visualfxtool.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>Captain Sim Menu</Name>
<Disabled>False</Disabled>
<Path>Captain_Sim\Captain_Sim.b757.menu.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>FeelThere PIC737X Helper</Name>
<Disabled>False</Disabled>
<Path>FeelThere\B737\PIC737XH.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>FeelThere CitationX Helper</Name>
<Disabled>False</Disabled>
<Path>FeelThere\CitationX\CitationXH.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>FeelThere EJetX Helper</Name>
<Disabled>False</Disabled>
<Path>FeelThere\E170\EJetH.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>FeelThere ERJX Helper</Name>
<Disabled>False</Disabled>
<Path>FeelThere\Erj\E145XH.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>Level-D Simulations</Name>
<Disabled>False</Disabled>
<ManualLoad>False</ManualLoad>
<Path>Modules\LVLD.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>PMDG Options</Name>
<Disabled>False</Disabled>
<Path>PMDG\DLLs\PMDGOptions.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>PMDG Events</Name>
<Disabled>False</Disabled>
<Path>PMDG\DLLs\PMDGEvents.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>PMDG Sounds</Name>
<Disabled>False</Disabled>
<Path>PMDG\DLLs\PMDGSounds.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>Maddog 2008</Name>
<Disabled>False</Disabled>
<ManualLoad>False</ManualLoad>
<Path>C:\Program Files\Microsoft Games\Microsoft Flight Simulator X\Modules\LeonardoSH.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>PMDG HUD interface</Name>
<Disabled>False</Disabled>
<Path>PMDG\DLLs\PMDG_HUD_interface.dll</Path>
<DllStartName>module_init</DllStartName>
<DllStopName>module_deinit</DllStopName>
</Launch.Addon>
<Launch.Addon>
<Name>Flight Recorder</Name>
<Disabled>False</Disabled>
<ManualLoad>False</ManualLoad>
<Path>Aerosoft\Flight Recorder\AS-FlightRecorder.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>FS Recorder</Name>
<Disabled>False</Disabled>
<ManualLoad>False</ManualLoad>
<Path>C:\Program Files\FS Recorder for FSX\FSRecorder_FSX.dll</Path>
</Launch.Addon>
<Launch.Addon>
<Name>FSUIPC 4</Name>
<Disabled>False</Disabled>
<Path>Modules\FSUIPC4.dll</Path>
</Launch.Addon>
</SimBase.Document>
Lastly, I do have an FSUIPC4.LOG file, I believe. Note that this is the log created when I started FSX while the original DLL.XML was renamed. Here it is:
********* FSUIPC4, Version 4.90 by Pete Dowson *********
Running inside FSX on Windows Vista
Module base=62C40000
User Name=""
User Addr=""
FSUIPC4 not user registered
WIDEFS7 not user registered, or expired
920 System time = 22/07/2013 16:46:12
920 FLT path = "C:\Users\Scott Pumphrey\Documents\Flight Simulator X Files\"
967 Trying to connect to SimConnect Acc/SP2 Oct07 ...
1014 FS path = "C:\Program Files\Microsoft Games\Microsoft Flight Simulator X\"
1669 LogOptions=00000000 00000001
1669 SIM1 Frictions access gained
1700 Wind smoothing fix is fully installed
1700 G3D.DLL fix attempt installed ok
1700 SimConnect_Open succeeded: waiting to check version okay
1700 Trying to use SimConnect Acc/SP2 Oct07
4321 Running in "Microsoft Flight Simulator X", Version: 10.0.61472.0 (SimConnect: 10.0.61259.0)
4321 Initialising SimConnect data requests now
4321 FSUIPC Menu entry added
4368 C:\Program Files\Microsoft Games\Microsoft Flight Simulator X\FLIGHTS\OTHER\FLTSIM.FLT
4368 C:\Program Files\Microsoft Games\Microsoft Flight Simulator X\SimObjects\Airplanes\Aircreation_582SL\Aircreation_582SL.AIR
61074 System time = 22/07/2013 16:47:12, Simulator time = 16:46:19 (23:46Z)
61433 Starting everything now ...
63617 Advanced Weather Interface Enabled
74084 Weather Mode now = Theme
74084 C:\Users\Scott Pumphrey\AppData\Roaming\Microsoft\FSX\Previous flight.FLT
85894 System time = 22/07/2013 16:47:37, Simulator time = 16:46:16 (23:46Z)
85894 *** FSUIPC log file being closed
Average frame rate for running time of 8 secs = 15.8 fps
G3D fix: Passes 9335, Null pointers 0, Bad pointers 0, Separate instances 0
Memory managed: 6 Allocs, 6 Freed
********* FSUIPC Log file closed ***********
If you need to see the log from starting FSX with the original DLL.XML, please let me know.