With any luck the attached file should demonstrate the problem. If not, I have attached a screenshot of how it looks on my machine.
I am getting strange diagonal glow effects with a glowing flat. It must be something specific to the level because I have not seen this in other levels with the same GLDEFS loaded. However, I have managed to cut this map down to only the area where the problem exists.
The only shader option that makes a difference to this is, not too surprisingly, the one for glowing textures: switching it off switches off the glow and, of course, the error.
