Most of the time (80-90%), the crashes on fast travel/normal travel into Novac are the result of a corrupt save game, or a mod that has some kind of AI and level list/equipment conflict with the Novac cells. In most cases it seems to be a combination of both, but the major underlying reason is ALWAYS going to be a corrupt save game.
After over 48 hours of hardcoe testing and data runs this is the only reason I can consistently find for all my crashes and for crashes which several very experienced modders/testers were having. In my case it was a corrupt save combined with a few overhaul/global change type mods.
I had this problem right after the 1.3 patch release, and solved it by going back about 50 saves and deleting all my corrupt and crashing save games.
Now with 1.4 and a complete reinstall of the game it was occuring again, but only on the last 10-15 saves I had made.
The best way to solve the crashes is to go back in your saves and find one where you can still fast travel to Novac. You might have to enter TMM 1 into the console if it is a game from before you got to Novac. You can go back to a clean save so you don't have all the markers revealed after that. That is the only thing that seems to work if you are having the CTDs.
Once you find a good clean save, then proceed on with game play. I can't find any other way to do this, and also if you do have a corrupt game, it will fubar and gork the whole rest of the game for you. Playing on a corrupt save is not something you should do, or can do for very long.
This is what will tell you if your save is corrupt. Let me say that in every instance of a corrupt save I tested, this was the one sure sign of that. If you have managed to get to Novac but then are crashing with more than 25-30 mods active, or find that you cannot fast travel with more than 25-30 mods activated, then you have a corrupt save, no debate possible.
If you are still having crashes on fast travel with a clean save, or loading a clean save inside Novac, then uncheck all your mods on a clean copy of an uncorrupted save. Fast travel to Novac and then start activating mods until you start getting crashes and hangups. I know it is a pain in the processor, but this was the only way I was able to stop the crashes and continue on with the game. You will be able to find the conflicting mods in your load order and then can eliminate those and move on. You will probably end up killing off some well loved mods, but in this case there is literally no choice.
I restarted the game with no mods active, made a clean save outside of Doc's house, then tried to fast travel to Novac. That way I knew I was going from a game that worked. Did it this way to ensure that corruptions in my old saves were not still causing the crashes.
Here is a list of mods that I can prove will crash the game around the Novac area. Still working out exactly why some of them do it, but it is definitive that they do in fact cause CTDs and locked up loads after you get to Novac.
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Vurt's WFO version 1.7- [Some sort of mesh/texture error. I rolled back to 1.6 and could fast travel and load a save in the Novac area. Have some screens of the trees around Novac which show a mesh problem in the areas on the interstate (near Dinky) and around the beginning of the road to Reppconn.]
Increased Wasteland Spawns- [Had over 25 crashes with the plugs and .esm active, none on fast travel since deactivating it. This mod has massive AI/level list conflicts after the 1.3 patch, and even worse on 1.4. The whole area around Novac seems to compound and magnify whatever general AI/level list fault is in conflict with IWS.]
Better Loading Screens- [Not sure why, but there is an overall problem with the memory involving the loading commands and routines in the vanilla game]
WARZONES - Misanthropy Pure- [Don't know why or even care right now. Too many crashes with this in other areas and cells, not just Novac. Some people can play this mod just fine, but I see a lot that can't for some reason or other. No disrespect to MGE, but I can't use this mod at all.]
Simple Streelights- [If it is misplaced in the load order it will cause crashes in Novac and the surrounding cells, especially around Electro City headquarters and Helios One. I had to play with the order for a bit, still not sure if it will cause other crashes or not. I have seen a lot of reports saying it has a general conflict, but they were varied as to the causes.]
1aNovacPlayersRoom- [Causes crashes about 75% of the time, and with it unchecked had no more crashes. Was the last thing I deactivated before my game stopped crashing in Novac. This mod also inserts items like Junders Plunkett's finger, Cook Cook's stew, and human remains into various fridges all over the wasteland, so there is a whole lot of general conflicts with the mod. Still an alpha anyway, so my fault for not trying it a few times on a clean save.]
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Those are the ones I found, but I'm sure there are a few more I don't use that will cause the same type of crashes. The problem seems to be with the male and female Novac citizens that you see the first time you FT into Novac. Those two seem to cause all the level list and AI conflicts. I have screen shots and error logs to prove it, but I am not Obsidian or gamesas, so I unable stop it or fix that game engine problem.
This was the load order/mod list I was running with the crashing and conflicting mods. I was still working on unchecking and checking when I exported.
[X] FalloutNV.esm
[X] IWR.esm
[X] MoraelinsMaces.ESM
[X] More Perks.esm
[X] More Perks for Companions.esm
[X] Caliber.esm
[X] WARZONES - Misanthropy Pure.esm
[X] ELECTRO-CITY - CompletedWorkorders.esm
[X] ELECTRO-CITY - Highways and Byways.esm
[X] Project Nevada - Core.esm
[X] Project Nevada - Equipment.esm
[ ] NVR-Strip.esm
[X] IWS-Core.esm
[X] MoMod.esm
[X] IWR - Rebuilt.esp
[X] OperationFixedTerrain.esp
[ ] SimpleStreetLights.esp
[X] VMS44Fixed.esp
[X] Brotherhood and House Alliance.esp
[X] Portable Tent.esp
[X] UHNV.esp
[X] UHNV-More Mannequins.esp
[X] PerkEveryLevel.esp
[X] More Perks Update.esp
[X] More Perks for Companions Update.esp
[X] Improved Sound FX.esp
[X] Improved Sound FX - Gunshot Distance Tweak.esp
[X] Improved Sound FX - Weapon Sharing Fix.esp
[ ] Devil'sMistressReturns.esp
[X] WeaponsOfTheShogunate.esp
[ ] BOAt51b.esp
[ ] Boacombat2glove.esp
[ ] Colossus NV.esp
[X] DragonskinTacticalOutfit.esp
[X] DragonskinBonusPack.esp
[X] Glove_be_gone.esp
[ ] HDTshop.esp
[X] NCR Rearmament v1.5.esp
[X] Neckchains.esp
[ ] sjs_bellydancedress.esp
[ ] jailhouserockette.esp
[X] GBetterhokers.esp
[ ] NVType3 Bone Armor.esp
[X] MoraelinsProfessionalsSuitMod.esp
[ ] NVLadyoutfitXOH.esp
[X] boa ncrpahelmet.esp
[X] manwithnoname.esp
[X] ilbuonorevolver.esp
[X] clintsfistfulrevolver.esp
[ ] Bandshirts_NV.esp
[ ] NWIxiaarmor1.esp
[ ] Nidaoutfitv1.esp
[ ] MoraelinsMacheteReplacer.esp
[ ] AllCompanionsEssential 2.0.esp
[ ] Follower Home Marker.esp
[ ] Bella.esp
[ ] RWKNV.esp
[X] Light Step ED-E.esp
[X] NiceCass.esp
[X] SweetVeronica.esp
[ ] NVWillow.esp
[X] six Try.esp
[ ] AWSW.esp
[X] BetterLoadingText.esp
[X] FNVIcons.esp
[X] NewRecipes.esp
[ ] NV Interiors - West Vegas Fringe.esp
[ ] NV Interiors - El Ray Motel.esp
[ ] NV Interiors - Cottonwood Cove.esp
[ ] 1aNovacPlayersRoom.esp
[ ] SecretStash80.esp
[X] Imp's Timescale Adjuster.esp
[X] ELECTRO-CITY - Inventory Sorters Compatibility Patch - RegularCATEYEvalue.esp
[X] Fellout.esp
[X] Interior Lighting Overhaul-Realistic Interiors-Full.esp
[X] Project Nevada - Cyberware.esp
[ ] Ahzteks Pistol and SMG Replacements.esp
[ ] NVFR-Version 1.esp
[ ] NVR-Version_10.esp
[ ] NVR-NPCs.esp
[ ] NVR-ELECTRO-CTIY_Patch.esp
[X] IWS-Core-Patrols.esp
[X] IWS-AS-LowSpawns.esp
[X] MoMod-Aliens.esp
[X] MoMod-Terminators.esp
[X] Vurt's WFO.esp (Version 1.7)
[X] Ahzteks Weapon Overhaul.esp
[X] CaliberX_Ammo_Update_1dot3.esp
[ ] Master Merged.esp
This is the load list I am running now. I had to arrange it by hand, BOSS just made it worse when I tried to use it.
[X] FalloutNV.esm
[X] IWR.esm
[X] MoraelinsMaces.ESM
[X] More Perks.esm
[X] More Perks for Companions.esm
[X] Caliber.esm
[X] Project Nevada - Core.esm
[X] Project Nevada - Equipment.esm
[X] ELECTRO-CITY - CompletedWorkorders.esm
[X] ELECTRO-CITY - Highways and Byways.esm
[X] NVR-Strip.esm
[X] MoMod.esm
[X] Project Nevada - Cyberware.esp
[X] IWR - Rebuilt.esp
[X] OperationFixedTerrain.esp
[X] SimpleStreetLights.esp
[X] VMS44Fixed.esp
[X] Brotherhood and House Alliance.esp
[X] Portable Tent.esp
[X] UHNV.esp
[X] UHNV-More Mannequins.esp
[X] PerkEveryLevel.esp
[X] More Perks Update.esp
[X] More Perks for Companions Update.esp
[X] Improved Sound FX.esp
[X] Improved Sound FX - Gunshot Distance Tweak.esp
[X] Improved Sound FX - Weapon Sharing Fix.esp
[X] Devil'sMistressReturns.esp
[X] WeaponsOfTheShogunate.esp
[X] BOAt51b.esp
[X] Boacombat2glove.esp
[X] Colossus NV.esp
[X] DragonskinTacticalOutfit.esp
[X] DragonskinBonusPack.esp
[X] Glove_be_gone.esp
[X] HDTshop.esp
[X] NCR Rearmament v1.5.esp
[X] Neckchains.esp
[X] sjs_bellydancedress.esp
[X] jailhouserockette.esp
[X] GBetterhokers.esp
[X] NVType3 Bone Armor.esp
[X] MoraelinsProfessionalsSuitMod.esp
[X] NVLadyoutfitXOH.esp
[X] boa ncrpahelmet.esp
[X] manwithnoname.esp
[X] ilbuonorevolver.esp
[X] clintsfistfulrevolver.esp
[X] Bandshirts_NV.esp
[X] NWIxiaarmor1.esp
[X] Nidaoutfitv1.esp
[X] MoraelinsMacheteReplacer.esp
[X] AllCompanionsEssential 2.0.esp
[X] Follower Home Marker.esp
[X] Bella.esp
[X] RWKNV.esp
[X] Light Step ED-E.esp
[X] NiceCass.esp
[X] SweetVeronica.esp
[X] NVWillow.esp
[X] six Try.esp
[X] AWSW.esp
[X] FNVIcons.esp
[X] NewRecipes.esp
[X] NV Interiors - West Vegas Fringe.esp
[X] NV Interiors - El Ray Motel.esp
[X] NV Interiors - Cottonwood Cove.esp
[X] SecretStash80.esp
[X] Imp's Timescale Adjuster.esp
[X] ELECTRO-CITY - Inventory Sorters Compatibility Patch - RegularCATEYEvalue.esp
[X] Fellout.esp
[X] Interior Lighting Overhaul-Realistic Interiors-Full.esp
[X] Ahzteks Pistol and SMG Replacements.esp
[X] NVFR-Version 1.esp
[X] NVR-Version_10.esp
[X] NVR-NPCs.esp
[X] NVR-ELECTRO-CTIY_Patch.esp
[X] Vurt's WFO.esp (Version 1.6)
[X] MoMod-Aliens.esp
[X] MoMod-Terminators.esp
[X] Ahzteks Weapon Overhaul.esp
[X] CaliberX_Ammo_Update_1dot3.esp
[X] Master Merged.esp
No crashes in the last 10 times I fast traveled and no crashes the last 10 times I walked in from different spots surrounding Novac like Helios One, Gibson's, Toxic Dump Site, Reppconn, and Ranger Station Charlie. I had a string of corrupted saves and conflicting load lists on two different games on two different computers, so I know this is what works to solve the CTDs.
Hope this helps everyone having this problem. I know I have seen an awful lot of complaints and posts all over the net, not just on Nexus and gamesas.