So I've been having a very strange problem with Fallout recently. It appears that whenever certain objects enter the frame, the graphics totally wig out and go insane, however the game is still playable. The common thing that happens is that the entire screen turns green (occasionally yellow) save for whatever object seems to be causing the issue, which often appears as a blue, pink, or purple haze or outline. There's a few specific objects that I can name that trigger this effect: Wadsworth, the use of a Stealth Boy, cloaked Infernal (Imperial?) Dragoons, the dead body of a Chinese soldier when it fades out of existence. I'd love to simply wipe the game out and reinstall it or whatever, but unfortunately the disks are several states away and I'd rather see if there's a different way around it.

Possible causes of these issues:

• Recently activated the 4th CPU core on my motherboard
  
• Switched out old graphics card for a Sapphire Radeon 6850 HD
  
• Had previously done a lot of work in FO3's ini file to try to optimize gameplay, which may not reflect the current system's setup

Any help or pointers would be greatly appreciated! Thank you!

I have a fresh install of Fallout 3 and had the same problem right at the start of the game, at the birthday party, and soon after out of the vault.

same question here (not answered):
http://www.gamesas.com/index.php?/topic/1199650-graphics-glitch/page__view__findpost__p__17858007__hl__screen__fromsearch__1

That thread suggests reducing antialiasing, filtering etc. I tried the same and it seemed to work. But that is, of course, not a fix.

I'm using:
- Dual Core Pentium E5700
- Radeon HD 5570