I've commented out the offending line in the error and have since moved through several others - commenting out references to materials. Will post results when I'm done sifting through the issues.

Somewhat of a success.

The MDC stuff and a couple of other mods are showing up in the scene editor now. However, there are still several mods missing; like the MP3 and Unitec bunker stuff. Am not receiving any errors at launch, yet have once again encountered the issue of several mods not showing up in the scene editor.

Does anyone have any ideas as to how to go about fixing it?