Ok. I did this, cut the xserverx graphics back to my home (i'm using linux), and restarted netradiant, but I got this in the console:
OpenGL window configuration: colour-buffer = 32bpp, depth-buffer = 24bpp
Unable to find default tag file /home/john/netradiant-395-x86/trem.game/shadertags.xml. No tag support.
OpenGL window configuration: colour-buffer = 32bpp, depth-buffer = none
Model load failed: "models/buildables/mgturret/mgturret.md3"
entityCreate -class team_human_mgturret
I'm not sure how useful the first three lines are, but they might be linked to:
Lighting mode requires OpenGL features not supported by your graphics drivers:
GL_ARB_shader_objects
GL_ARB_vertex_shader
GL_ARB_fragment_shader
GL_ARB_shading_language_100
Which appeared just before.
I also have a screenie of what happens when I try and load it (attached)