It was working until I defeated the Legion in a quest from NCR to explore a town hall. Since then, vendors indoors will always crash the game as soon as I hit "accept".

I only found one download that says it can fix this but it is from some for profit MOD site that forces all users to register and pay to download it. I cannot play this game if I cannot buy and sell items.

I expect GOG to offer a patch to fix this. I use Windows 7.


GREAT NEWS

I got this game working with no more crashes each time I try to buy/sell by downloading the Direct X using this site. The fix worked!