OK, The Blackscreen Issue...
Are you running stock graphic settings (in game)?
If I use stock graphic settigns : Black Screen
I did try to tweak some of my 3D parameters which none fixed the problem :
Disabling Physx Effect
Modification for the 3d Effect for Fallout3.exe
Inside the fallout setting I disabled V-Sync which fixed nothing.
Have you tried going from full screen to windowed, and back?
Yes I did with the same result.
Are there any artifacts before, or after the blackscreen?
The image freeze and then black screen and then animation resume to freeze again followed by another black screen, after two shot I get a complete lock up and I have to ctrl-alt-del to go out OR the system revert to windows stating a problem with Fallout3 and something like "Display stop responding".
Do you notice any type of situation, in game, prior to the blackscreen that you could say is a trigger? For example: Shaders, Smoke, Fog
Nope, wathever the save I load or even if I start a new game the freezing and black screen happens in the few seconds of the gameplay but never at the EXACT same spot. Sometimes I am SO lucky I can play as much a 28 seconds ;p)
And lastly, your PC, Pre-built? If so, make/model
If custom built, Motherboard / BIOS
Custom built :
Gigabyte motherboard, GA-965P-DS3 with Bios Revision F10
I know a couple of guys who were having that issue, whom were using PC's that I built for them. Installing the Motherboard driver, and/or updating the BIOS fixed the issue. Not saying that's your issue, but it's something to consider if it's a custom built machine.
Be prepared for more questions.
~~Haxsys