The 777-200 Base Pack v1.0 has its own sounds, KB #7442 doesn't apply.

The sounds are working fine for me. Check inside the dll.xml file to make sure you have this entry:

<Launch.Addon>
   <Name>Captain Sim 777 Sound</Name>
   <Disabled>False</Disabled>
   <Path>Captain_Sim\777\cs.sound.dll</Path>
</Launch.Addon>

And make sure that the cs.sound.dll is in the <FSX>Captain_Sim\777 folder.

Note. In your case, make sure it's in the <P3D>\Captain_Sim\777 folder.