This is what is in my FSX-SE DLL.XML file:

<?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>
  <Launch.Addon>
    <Name>FSUIPC 4</Name>
    <Disabled>False</Disabled>
    <Path>Modules\FSUIPC4.dll</Path>
  </Launch.Addon>
  <Launch.Addon>
    <Name>Captain Sim 777 Sound</Name>
    <Disabled>False</Disabled>
    <Path>Captain_Sim\777\cs.sound.dll</Path>
  </Launch.Addon>
  <Launch.Addon>
    <Name>Captain Sim 520 Menu</Name>
    <Disabled>False</Disabled>
    <Path>Captain_Sim\520\cs.sound.dll</Path>
  </Launch.Addon>
  <Launch.Addon>
    <Name>Captain Sim 727 Menu</Name>
    <Disabled>False</Disabled>
    <Path>Captain_Sim\727\Captain_Sim.p727.menu.dll</Path>
  </Launch.Addon>
  <Launch.Addon>
    <Name>Captain Sim 707 Sound</Name>
    <Disabled>False</Disabled>
    <Path>Captain_Sim\707\cs.sound.dll</Path>
  </Launch.Addon>
  <Launch.Addon>
    <Name>Captain Sim 737 Sound</Name>
    <Disabled>False</Disabled>
    <Path>Captain_Sim\737\cs.sound.dll</Path>
  </Launch.Addon>
  <Launch.Addon>
    <Name>Captain Sim 757 Sound</Name>
    <Disabled>False</Disabled>
    <Path>Captain_Sim\757\cs.sound.dll</Path>
  </Launch.Addon>
  <Launch.Addon>
    <Name>Captain Sim 767 Sound</Name>
    <Disabled>False</Disabled>
    <Path>Captain_Sim\767\cs.sound.dll</Path>
  </Launch.Addon>
  <Launch.Addon>
    <Name>Captain Sim Sound</Name>
    <Disabled>False</Disabled>
    <ManualLoad>False</ManualLoad>
    <Path>Captain_Sim\bin\cs.sound.dll</Path>
  </Launch.Addon>
</SimBase.Document>


So I suggest you copy your DLL.XML file from the the %AppData%\Microsoft\FSX folder to the %AppData%\Microsoft\FSX-SE folder, THEN deletete everything in it, and REPLACE it with the following and save it:

<?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>
  <Launch.Addon>
    <Name>Captain Sim 757 Sound</Name>
    <Disabled>False</Disabled>
    <Path>Captain_Sim\757\cs.sound.dll</Path>
  </Launch.Addon>
</SimBase.Document>

See if that helps.