I started the game a couple of days ago and happen to be running into the very same problem.
If you are playing the game with german language, try this fix:
https://www.the-witcher.de/dlfile--id-284.html For some reason, the game sometimes crashes when there are umlauts displayed on screen, like in dialogue subtitles or at merchants.
The fix changes ä/ü/ö to ae/ue/oe, which obviously isn't the best way of fixing the problem, but so far it works for me.
You can of course also switch to another language.
There is, however, this message board post from a german player, for whom the fix didn't work.
See this discussion:
http://extreme.pcgameshardware.de/rollenspiele-und-adventures/442043-witcher-2-crash-ohne-fehlermeldung.html And while we are at it: What does CDPR have to say about it? Doesn't sound like a problem needing much work to get solved.