I haven't played Fallout 3 since the release of New Vegas, and have been looking forward to replaying it for weeks now.
It's great to be back, but I'm having several problems that seem to be getting progressively worse.

1. Freezing. This first happened a few times while I was playing the Operation Anchorage DLC. Now it happens much more often, at times it also happens upon entering a cell. I've disabled auto-save, which seemed to help somewhat at first, but it doesn't stop the freezing.

2. Black screen upon entering a cell. This first happened in Arefu when I entered the West's residence. Upon entering, the game starts loading, then the screen goes/stays black, though the background music keeps playing. Quitting/restarting doesn't help. I left the quest alone and did some other stuff first, after that I was able to go back and complete the quest. Now it happens more often though.

3. Pre-mature arrival of the Enclave. Right now, I'm playing the 'Waters of Life' quest. I was on my way to drain the intake pipes, but seconds after I enter the first section of the pipe, the game freezes. So I haven't been able to drain the pipes, nor did I see the Enclave vertibird arrive. I loaded up a quick save and quickly left the Jefferson facility. I left for Dukov's place and received a warm Enclave welcome.

The arrivial of the Enclave doesn't bother me at all, but I thought it might be of some use to post it.

I've really been enjoying my replay of Fallout 3, but the freezing and black screens make it unplayable for me. Any help would be appreciated. Before I started playing Vegas, I've played Fallout 3 for hundreds of hours without any of these problems, which makes it even weirder for me.

Though there is one thing. About halfway through Vegas, my videocard died and was replaced. Could this be a problem factor?

If the replacement graphics card wasn't the exact same make, model, etc, yes it could. Did you move the INI file out of the saves folder to force the launcher to generate a new one?

No, I haven't... the Fallout 3 ini or the preferences ini?

I imagine it will be the Fallout3 one, don't you think? I don't recall what's in either one any more (FO3 is getting old, I haven't played it for some while). Both of them are text files, open them in notepad to see which one mentions system hardware.

I'm not sure, I've never tampered with the ini files. I'll back them up just in case.
Anyway, thank you very much This makes sense, hope I'll be able to continue my playthrough without anymore (big) problems!

Well, I moved both ini files out of the folder and had the game generate new ones. It displayed a message about detecting my hardware and generated new files.
I went back to the pipe in Jefferson Memorial, the one location where it would *always* freeze on me. Got through the first section, drained the pipes in the second section and watched the Enclave arrive. Entered the third section, the screen goes/stays black.......

Any other ideas...?

Pretty please...??