Hello, Been working on a test/sandbox map. I imported a heightmap generated with L3DT, which is 2048x2048, 16-bit PNG. I've set up a water plane. I've set up have set up a decoration object, using one of the included grass textures. This decoration object only shows up on the grass texture layer. I've set up two layers of my own textures (grass and rock), using the "flood fill" option, to place rock texture only on steep surfaces, etc. Everything up to this point was fine. Terrain runs smoothly, no problems. In running around, I noticed the grass decorator is showing up under water, which I don't want. So... I added a 3rd, sand, layer to paint below the waterline, where the grass won't show up (since it's limited to the grass texture layer). The sand material/texture is the one included with the default install of T3D. Upon painting this texture, my character fell through the terrain, and now nothing I do is correcting it. I recreated the terrain, and have the same issue. So, I have no idea what's going on, or why painting a 3rd texture is causing the terrain to stop colliding... but... well, that's why I'm posting about it here :) As for the "other weirdness", every now and again, different objects will get "locked" to other ones. For example, I was trying to move the player drop object above the ground (since, for some reasin, every time I import a heightmap - even if it's the same one - it seems to import at random heights (more on this later), so I have to adjust the player drop and/or the water plane so they're correctly positioned. Anyway, what will happen at random is that the player drop, for example, will get "locked" to the terrain. So, if I move the player drop, the terrain is moving with it. It's happened when trying to move the water plane as well. I have to reopen the map in order to fix it. Very odd issue. The main issue, though, is the random falling through the terrain? Any idea of why this might be happening? Thanks.