Walls are "flashing"

[Codex]

Hi!

My name is Mathias and I'm new when it comes to programming and such - but I still find it very interesting!
I've just created my first room in the HPL2 level editor, and I know how to play the map and all that - but my problem is; that the walls are "flashing" (and the floor/roof) when I'm moving around in the room in my map. In the level editor nothing it also "flashes/bugs". When I stand still, everything is fine - but as soon as I move my mouse the walls are "flashing" between black and the original material color.
Help please?

EDIT:
I might have posted this in the wrong section - sorry for that!

EDIT 2:
I've re-posted this in the Custom Stories & Modifications section.

Thanks

[TFEF]

This usually happens because two objects (in this case, walls) are occupying the same space. Just give them a little bit of space, but so they're still touching in the Level Editor.

[Roenlond]

Yeah, overlapping textures will cause that problem. Moving the floor/walls 0.01 units in the respective direction is usually enough and won't be noticeable. You may also hide it on walls (and certain other objects )by using the welder or pillar objects since that usually looks more realistic.