I'm trying to load an interior I made in Torque Constructor in MBP 1.50 Beta 3, since it uses multiplayer textures. However the game crashes when I load any map if the .dif file is present anywhere in the game's folders in a subfolder in the data folder. Usually the only problem I have with interiors is the map2dif not working so I'm confused about what's happening.
EDIT: I can load a level if I put the interior in a .zip file, but when I try to load the interior via the level editor I get a message saying "Disconnected: Error: Invalid packet".
At first I thought I needed to rename the folder where my texture album points to from "MBPlatinum" to "MBP" so the game would recognize them, but it did not work either. There are also no "red lines" in the map file.
This might not be what's causing the issue, but make sure the directory "platinumbeta\data\multiplayer\interiors" contains all of the textures your interior uses. If there are any textures used by your interior not present there, add them in, otherwise you will get the "Error: Invalid Packet" message when trying to load it due to missing textures.
Edit: I just tried to place your interior in a level in Beta 3, and it loaded just fine without any issues. I'm pretty sure the reason it's not working for you is because of the missing textures issue I mentioned, just make sure the directory I mentioned contains all of the textures used by your interior and it should load properly.