There is a ton of topics on this already and no apparent solution but I just wanted to share a few things I have done that may have fixed it. I have played the game for several hours (began with a new quest, already on broken steel quests) with no freezing and no CTDs either, so I'm convinced it did something. I wanted to share my findings with everybody to try and see if that is indeed the case.

Few things, by freezing I mean that the game will freeze but the music continues to play and usually happens upon entering a house or new area. The only way to close the game is by opening the task manager via cntrl-alt-del and ending the fallout3.exe process. This is commonly reported on Windows 7 (both 32-bit and 64-bit editions) leading most users here to believe it is a WIndows 7 issue, but if you search for "fallout 3 Vista freeze" on google, you'll bring up plenty of links describing the exact same problem on Vista which is a supported operating system by Fallout 3 (windows 7 is not officially supported). Once again, it is NOT a Windows 7-exclusive problem, happens in Vista as well.

It appears to be related to loading since it happens often when entering a house/building/new area. I've had it happen in the wasteland a couple times while the game was streaming new stuff in the background, and I've had it happen after my character dies right as it's re-loading a save. It's not a save problem since turning off auto-save on entering buildings does not prevent it. It's not a ffdshow issue since I do not have that on my system. Doing a google search shows that the issue has always existed since the game was released, but it appears only quad core users reported it. Most every user who reports it is running a core i processor which except the i3 are multithreaded (4+ threads) but it happens on i3 as well.

I'll start with the infamous iNumHWThreads= fallout.ini addition. This does limit the number of hardware threads accessible by fallout 3. If I set it to 2, the RendererInfo text file reports that I have 2 HW threads. (If I leave it alone it says I have 8). I initially made some INI changes including the iNumHWThreads=8 which in practice did absolutely nothing since it would've used 8 anyways (I didn't know at the time), but freezing happened less frequently.. possibly because of INI changes, definitely not because I manually set it to 8. Most users agree to set this to 2. Yes, this limits the amount of threads the game will use, but in my testing it does not negatively affect performance. The game may be multi-threaded, but it mostly uses one thread. Using fraps runs outside Megaton showed a minimum/average FPS increase setting this to 2. Rivet City marketplace has a burning barrel and many NPCs that slow FPS on most systems. Again, I had a minimum/average FPS gain with iNumHWThreads=2. (I thought about it, the gain could also be the Intel turbo boost but I'll definitely take it anyway if it helps with freezing)

I have 8GB of RAM in my system, but 32-bit apps like Fallout 3 cannot access more that 4GB. Fallout 3 cannot access over 2GB because it lacks the largeaddressaware header in it's executable. That means Windows will only allow it 2GB and conserve the remainder for itself, but this creates a problem because the game still sees 4GB and if it tries to access more than 2GB it will crash. There is a largeaddressaware 'patch' on fallout3nexus which will add the header and allow it to access the full amount. Even if you have a 32-bit OS, there are instructions that will allow it to access a little more RAM than it currently does. Fraps showed no change in performance using the largeaddressaware mod, but I have definitely noticed less stuttering throughout the game and no CTDs in several hours of gameplay.

I tried all those background loading and multi threading INI changes from here: http://www.tweakguides.com/Fallout3_10.html and again using fraps there is no change in framerate with or without them. Keep in mind that some of the lines are turned on by default whether you have a multicore cpu or not, so we don't even know if the game uses them or uses them the way we think it does. I can report that there is no negative performance from using them so I do recommend having them on:

bBackgroundLoadLipFiles=1
bLoadBackgroundFaceGen=1
bBackgroundCellLoads=1
bLoadHelmetsInBackground=1
iBackgroundLoadLoading=1
bBackgroundPathing=1
bBackgroundNavmeshUpdate=1
bCloneModelsInBackground=1
bUseThreadedBlood=1
bUseThreadedMorpher=1
bUseThreadedTempEffects=1
bUseThreadedParticleSystem=1
bUseThreadedAI=1
bUseMultiThreadedFaceGen=1
bUseMultiThreadedTrees=1
iNumHavokThreads=5

A few will already be set to 1 by default. Also, I raised the following lines as recommended by the guide so the game uses more memory:

uInterior Cell Buffer=16
uExterior Cell Buffer=102
iPreloadSizeLimit=104857600

Again, identical performance reported by fraps either way, but I kept these new values anyways because I figured it wouldn't hurt and might prevent freezing. If you want to experiment with any of the other settings from that tweak guide, do NOT mess with the use30shaders line, leave it at 0. Supposedly, setting it to 1 and copying around the shader files will force 3.0 shaders but I experienced reduced performance in certain areas of the game (like rivet city marketplace or the area on mothership zeta where the NPCs hang out) so I'm not convinced this forces 3.0 shaders at all (which modern cards are better at than 2.0 shaders according to 3dmark06) and recommend highly it be left alone.

So that's what I did and like I said, several hours in and no freezing, no CTD. I'm convinced something I've done here made some sort of difference, but I'm not sure which one it was (hence the long post). The ini mods above might be legacy items for the engine and not even do a single thing for fallout 3 for all we know, but from my testing it doesn't hurt so I left them there. At the very least, if you are using 64-bit Vista/Windows 7 try out the largeaddressaware thing especially if using a lot of mods because it has been reported to help

Wanted to add a couple things I forgot to mention....

Make a backup of fallout.ini before tinkering with it. This is just for fallout.ini, you don't have to touch falloutprefs.ini. These fallout.ini 'suggestions' have been around forever, many of them were recommended for Oblivion. But one would think the developers have them set a certain way for a reason, and like I said for all we know they don't do anything. They don't seem to hurt anything either, which is why I'm leaving them in. If you run the largeaddressaware patch, obviously make a backup of fallout3.exe as well.

And the freezing may still be there, I have just not encountered it in 20 hours of gameplay which is promising so I wanted to share what I did. Not presenting this as a fix at all like some other threads I've read where a person will say "updated my klite codecs, no more crashes!" or my personal favorite "no freezing after defragging". Defragging - the ultimate placebo fix. In my 15 years of using PCs, I can't think of one problem that was ever fixed by a defrag that wasn't placebo.

I also run Fallout 3 on a windows 7 64 bit machine. I have not changed anything to the ini file. I also have not installed any user made mods.

So far I have played > 30 hours and I can't remember it crashing once. I only recently updated my Fallout 3 to version 1.7 (version 1.0 before that) along with all DLCs and this, luckily, did not make the game crash often.

My computer is much better than the recommended system requirements and I also play the game from an ssd. However even when playing it on my Dell Studio 1555 laptop (I managed to play it about medium settings) it rarely crashed.

I have always wondered why Fallout 3 always seems to crash on other peoples systems. I find it hard to believe it is simple luck that Fallout 3 never crashes for me.


Question to Unwinding: Did Fallout 3 crash often before you made these changes?

Question to other forum users: What are your experiences with Fallout 3 on a windows 7 (32 bit or 64 bit) computer? Does it crash often, rarely or never?

Thank you for this guide, it fixed the game for me. I only hope new vegas doesn't suffer the same problems. Also got a significant increase in FPS (30 FPS).

I played the vanilla FO3 (no dlc, not GOTY) on both Vista and Windows 7 (both 64-bit) pretty extensively with no crashes at all and only odd physics glitches. It was only after installing the GOTY edition with the extra content when I began experiences CTDs, but it wasn't like they'd happen every five minutes. More like every five hours or occasionally when exiting the game to windows. This was with a a core 2 duo processor, no mods, no edits to the .ini. The game would crash at places like the UFO or the riverboat, possibly due to DLC 'hooks'

Now that I have a 4-core/8-thread i7 I was pretty regularly getting freezing - not crashing. The game will freeze and the sound will keep playing which is what many other forum users are reporting with the core i series or quad core processors. It's definitely not a windows 7 issue at all, it's been reported since the game was released and has something to to with multi-threading. FO3 works just as fine on Win 7 as Vista

THIS FIX WORKS.

I recently bought the Steam Bethesda Pack, which includes what I assume is the GOTY edition of Fallout 3. I had first played Fallout 3 when it came out on the Xbox 360 and don't remember a lot of crashes, which makes sense because console hardware is more consistent across the board. Well, this new version of Fallout 3 was crashing all over the place. I was playing it on my HP ENVY 15, running Windows 7 Home 64-bit, and it was crashing more and more as I progressed, to the point where it was unplayable, crashing every time after a few minutes of play. Incidentally, while I did experience some of what are termed "freezes" (game stops working but sound continues) but a lot of them were full-on crashes. Frankly, the difference is academic for most practical purposes.

Well, I contacted tech support, and they told me first that my PC didn't meet specs, not realizing that an i7 at lower clock speed than a dual-core is actually a lot better than minimum requirements. I pointed this out, and they came back with Windows 7 being unsupported. OK, well, I didn't really expect them to be able to solve a crashing problem, but I wasn't very happy with abandonment. I wish they'd told me to come straight here instead. I found it later via the Vault wiki. And I'm glad I did, because after making all the changes listed and referenced by the OP above, the crashes have completely stopped. If you're wondering whether you should bother--bother, because something in there works. Like everyone else, I'm way too lazy to go through and figure out which specific item actually fixes it, but something did. Thanks very much for this post.

If Bethesda is reviewing this, I would ask (as a 25-year software developer and development manager myself) that you do have a QA person run through this list on a modern quad-core and see which item(s) fix crashes, because I think it's very likely that the problems will occur with Fallout New Vegas and anything else on the same engine unless it's been pretty substantially overhauled. I remember Oblivion being somewhat crashy, not as bad as this, but then I was running it on an older computer and OS. I don't think these problems are new and I don't think they are going away on their own. It would be pretty easy to make a couple of conservative changes to fallout.ini out of the box and reduce the number of crashes people are getting. I realize that all systems are different, but I think in the end it's going to be an item that is pretty central and basic.

I would go so far as to say that Morrowind, Oblivion and Fallout 3 are my favorite games of all time in a 30-year history of gaming, and I appreciate very much the work and, well, love that Bethesda puts into them. I mention this to make very clear that I'm not bashing the company when I say that they have also been some of the least stable games I've ever played. Please, guys, work on your threading models, exception trapping and default configuration settings, because it shouldn't be this painful to get these games running right. And if people like the original poster and the writer of the linked configuration guide solve some problems for all of us, please spread the news, not just on this forum but to your tech support people and anywhere else people are looking. Users don't care who came up with the answer - they just want to be pointed to the answer as fast as possible and get back into the game.

@GryphonQ

What are your system specs? I know you have a q-core cpu but what else do you have? Maybe you and the OP have a similair hardware setup.

I'm really not sure about this but, maybe, when you progress further through the game (played for a long time on one save) the game requires extra RAM memory.
Some of these fixes allowed the game to use more memory and maybe this made it more stable to play on one save for a long time.