* s/GL_CLAMP/GL_CLAMP_TO_EDGE/g (If this change appears to cause you problems

and you're using an nVidia graphics card, make sure your 'conformant texture
  clamp' setting is set to on for ioq3)

code/renderer/tr_bsp.c

@@ -205,7 +205,7 @@ static	void R_LoadLightmaps( lump_t *l ) {
 			}
 		}
 		tr.lightmaps[i] = R_CreateImage( va("*lightmap%d",i), image, 
-			LIGHTMAP_SIZE, LIGHTMAP_SIZE, qfalse, qfalse, GL_CLAMP );
+			LIGHTMAP_SIZE, LIGHTMAP_SIZE, qfalse, qfalse, GL_CLAMP_TO_EDGE );
 	}
 
 	if ( r_lightmap->integer == 2 )	{