I had been getting random crashing trying to play game. Usual 'FONV has encountered a problem' etc.
I received a mail from Bethesda Uk which has helped....
"At least some of your crashes appear to be related to an Arcsoft sound codec which is on your system. Please try going to C:\program files(x86)\common files\arcsoft\ and rename the asaudio file located here to asaudiobackup and then try the game to see if the stability improves".
Hope this may help someone else.
I saw a post somewhere here about a prog that blocked codecs and was plannig on trying it out but this mail was waiting for me when I got home so i tried it first and so far it has worked. The NPC dialogue is not audible but after what I have been through trying to get the game to work at all I am not too bothered about.
PC= Intel i7 975 @3.33GHz
6GB RAM
nVidia GeForce GTX 295