I'm not trying to fun either of Bethesda's (Obsidian's) Fallouts with Geforce graphics, and I have had no similar problem, however, beginning with the release of the GTX 460 last summer, Geforces have been problematic in Fallout 3 for many Geforce owners who upgraded their drivers or their graphics cards, and Fallout: NV fails with a very high percentage of game owners who have both Geforces faster than the old 8800s, and Windows Vista / Windows 7. You can run a search for the half dozen - plus workarounds that forum members have discovered and shared with one another here while we wait on a final, broad-spectrum permanent repair of the anti-Geforce bias in the game.