Ok I found your problem...
After deleting bits and bobs it turns out those rounded pillars under the wooden platform are causing the problem.
I deleted them and presto...Also your two wooden platforms were turned into displacements...Although that caused no problem but I suggest remaking it.
So to conclude: Delete those rounded pillars and to prove my answer:
** Executing...
** Command: "c:program filesvalvesteamsteamappshabboisourcesdkbinvbsp.exe"
** Parameters: -game "c:program filesvalvesteamsteamappshabboihalf-life 2hl2" "C:Documents and SettingsDELLDesktopTWHL3"
Valve Software - vbsp.exe (Jan 2 2006)
2 threads
materialPath: c:program filesvalvesteamsteamappshabboihalf-life 2hl2materials
Loading C:Documents and SettingsDELLDesktopTWHL3.vmf
fixing up env_cubemap materials on brush sides...
ProcessBlock_Thread: 0...1...2...3...4...5...6...7...8...9...10 (1)
ProcessBlock_Thread: 0...1...2...3...4...5...6...7...8...9...10 (0)
Processing areas...done (0)
Building Faces...done (0)
FixTjuncs...
PruneNodes...
WriteBSP...
done (0)
writing C:Documents and SettingsDELLDesktopTWHL3.prt...done (0)
Creating default cubemaps for env_cubemap using skybox materials:
skybox/sky_day01_01*.vmt
Run buildcubemaps in the engine to get the correct cube maps.
No such variable "$hdrbasetexture" for material "skybox/sky_day01_01rt"
Can't load skybox file skybox/sky_day01_01 to build the default cubemap!
Finding displacement neighbors...
Finding lightmap sample positions...
Displacement Alpha : 0...1...2...3...4...5...6...7...8...9...10
Building Physics collision data...
done (0) (182475 bytes)
Emitting linux collision data (use -nolinuxdata to disable).
Building Physics collision data...
done (0) (532937 bytes)
Placing detail props : 0...1...2...3...4...5...6...7...8...9...10
Compacting texture/material tables...
Reduced 317 texinfos to 224
Reduced 15 texdatas to 12 (519 bytes to 316)
Writing C:Documents and SettingsDELLDesktopTWHL3.bsp
2 seconds elapsed
Memory leak: mempool blocks left in memory: 3
** Executing...
** Command: "c:program filesvalvesteamsteamappshabboisourcesdkbinvvis.exe"
** Parameters: -game "c:program filesvalvesteamsteamappshabboihalf-life 2hl2" -fast "C:Documents and SettingsDELLDesktopTWHL3"
Valve Software - vvis.exe (Jan 2 2006)
fastvis = true
2 threads
reading c:documents and settingsdelldesktopTWHL3.bsp
reading c:documents and settingsdelldesktopTWHL3.prt
295 portalclusters
1047 numportals
BasePortalVis: 0...1...2...3...4...5...6...7...8...9...10 (1)
Optimized: 1814 visible clusters (0.00%)
Total clusters visible: 75165
Average clusters visible: 254
Building PAS...
Average clusters audible: 295
visdatasize:24427 compressed from 23600
writing c:documents and settingsdelldesktopTWHL3.bsp
1 second elapsed
** Executing...
** Command: "c:program filesvalvesteamsteamappshabboisourcesdkbinvrad.exe"
** Parameters: -game "c:program filesvalvesteamsteamappshabboihalf-life 2hl2" -noextra "C:Documents and SettingsDELLDesktopTWHL3"
Valve Software - vrad.exe SSE (Jan 16 2006)
--- Radiosity Simulator
--2 threads
[Reading texlights from 'lights.rad']
[45 texlights parsed from 'lights.rad']
Loading c:documents and settingsdelldesktopTWHL3.bsp
727 faces
1 degenerate faces
137942 square feet [19863760.00 square inches]
60 displacements
25282 square feet [3640680.25 square inches]
726 patches before subdivision
5383 patches after subdivision
0 direct lights
BuildFacelights: 0...1...2...3...4...5...6...7...8...9...10 (0)
BuildVisLeafs: 0...1...2...3...4...5...6...7...8...9...10 (9)
transfers 236362, max 293
transfer lists: 1.8 megs
GatherLight: 0...1...2...3...4...5...6...7...8...9...10 (0)
Bounce #1 added RGB(0, 0, 0)
Build Patch/Sample Hash Table(s).....Done<0.0068 sec>
FinalLightFace: 0...1...2...3...4...5...6...7...8...9...10 (1)
FinalLightFace Done
Ready to Finish
Computing detail prop lighting : 0...1...2...3...4...5...6...7...8...9...10
0 of 0 (0% of) surface lights went in leaf ambient cubes.
ComputePerLeafAmbientLighting: 0...1...2...3...4...5...6...7...8...9...10
Object names Objects/Maxobjs Memory / Maxmem Fullness
---------- ------------- ------------- ------ models 1/1024 48/49152 ( 0.1%)
brushes 68/8192 816/98304 ( 0.8%)
brushsides 499/65536 3992/524288 ( 0.8%)
planes 456/65536 9120/1310720 ( 0.7%)
vertexes 1402/65536 16824/786432 ( 2.1%)
nodes 432/65536 13824/2097152 ( 0.7%)
texinfos 224/12288 16128/884736 ( 1.8%)
texdata 12/2048 384/65536 ( 0.6%)
dispinfos 60/0 10560/0 ( 0.0%)
disp_verts 1724/0 34480/0 ( 0.0%)
disp_tris 2304/0 4608/0 ( 0.0%)
disp_lmsamples 64604/0 64604/0 ( 0.0%)
faces 727/65536 40712/3670016 ( 1.1%)
origfaces 376/65536 21056/3670016 ( 0.6%)
leaves 434/65536 13888/2097152 ( 0.7%)
leaffaces 779/65536 1558/131072 ( 1.2%)
leafbrushes 175/65536 350/131072 ( 0.3%)
areas 2/256 16/2048 ( 0.8%)
surfedges 4812/512000 19248/2048000 ( 0.9%)
edges 2650/256000 10600/1024000 ( 1.0%)
LDR worldlights 0/8192 0/720896 ( 0.0%)
HDR worldlights 0/8192 0/720896 ( 0.0%)
waterstrips 27/32768 270/327680 ( 0.1%)
waterverts 0/65536 0/786432 ( 0.0%)
waterindices 564/65536 1128/131072 ( 0.9%)
cubemapsamples 1/1024 16/16384 ( 0.1%)
overlays 0/512 0/180224 ( 0.0%)
LDR lightdata [variable] 252156/0 ( 0.0%)
HDR lightdata [variable] 0/0 ( 0.0%)
visdata [variable] 24427/16777216 ( 0.1%)
entdata [variable] 10570/393216 ( 2.7%)
LDR leaf ambient 434/65536 10416/1572864 ( 0.7%)
HDR leaf ambient 0/65536 0/1572864 ( 0.0%)
occluders 0/0 0/0 ( 0.0%)
occluder polygons 0/0 0/0 ( 0.0%)
occluder vert ind 0/0 0/0 ( 0.0%)
detail props [variable] 1/33300 ( 0.0%)
dtl prp lght [variable] 1/4 (25.0%)
HDR dtl prp lght [variable] 1/4 (25.0%)
static props [variable] 1/2864 ( 0.0%)
pakfile [variable] 15338/0 ( 0.0%)
Win32 Specific Data:
physics [variable] 182475/4194304 ( 4.4%)
Total Win32 BSP file data space used: 779616 bytes
Linux Specific Data:
physicssurface [variable] 532937/6291456 ( 8.5%)
Total Linux BSP file data space used: 1130078 bytes
Total triangle count: 1798
Writing c:documents and settingsdelldesktopTWHL3.bsp
11 seconds elapsed
** Executing...
** Command: Copy File
** Parameters: "C:Documents and SettingsDELLDesktopTWHL3.bsp" "c:program filesvalvesteamsteamappshabboihalf-life 2hl2mapsTWHL3.bsp"