I've been having this problem ever since I got out of Vault 101. The game runs a-ok as long as I can make it to Megaton within ten minutes, as it doesn't seem to crash in there. I was hanging around Megaton for about half an hour taking in the sights and chatting up the locals. I found myself on a quest from Moira to get a mine from Minefield, but I can't make it there because anytime I'm out in the open for more than ten minutes, the game crashes on me, giving me no explanation as to why. I've tried running in Windowed mode, but it didn't do me any good. I'm running on patch 1.7. I have no desire to post a DXDiag as I know full well my system can run it, I'd just like to know a workaround to all this crashing. I've played with and without the very few mods I have installed and I've had no luck in being able to explore.
First crash occurred when I reached the gate to Megaton both times, reloaded, made it into Megaton and all was fine while I was in there. Second crash happened the second I was attacked by a group of raiders near Minefield. I don't know that that's going to help solve this, but hey, you never know. I chalked the first crash up to a virus scanner updating, but the others there was nothing else running in the background. At first I was playing on the highest graphical settings, now I play on the lowest and I have the same problems either way. I could live with crashing every three hours or so, but every ten minutes is ridiculous.