The surfaces in question are mostly flat, not sloped.
The map itself is rather large:
Object names Objects/Maxobjs Memory / Maxmem Fullness
------------ --------------- --------------- --------
models 393/400 25152/25600 (98.3)VERY FULL!
planes 11185/32767 223700/655340 (34.1)
vertexes 25644/65535 307728/786420 (39.1)
nodes 13711/32767 329064/786408 (41.8)
texinfos 4413/32767 176520/1310680 (13.5)
faces 18959/131071 379180/2621420 (14.5)
clipnodes 31113/32767 248904/262136 (95.0)VERY FULL!
leaves 8112/8192 227136/229376 (99.0)VERY FULL!
marksurfaces 24947/65535 49894/131070 (38.1)
surfedges 84126/512000 336504/2048000 (16.4)
edges 46110/256000 184440/1024000 (18.0)
texdata [variable] 3787328/4194304 (90.3)VERY FULL!
lightdata [variable] 4177326/4194304 (99.6)VERY FULL!
visdata [variable] 405638/2097152 (19.3)
entdata [variable] 129799/524288 (24.8)
=== Total BSP file data space used: 10988313 bytes ===
Possibly that is causing this?Any ideas what the problem might be?