UK_John: I am having the same problem with 1.2 "game is incomplete or version incompatible". I had the same error with the 1.01, but solved it by running it from the downloads folder in the Witcher 2 folder in My Documents. 1.2 doesn''t run and gives me the above error wherever I run it from.
I have so much grief with this game with anything outside of the game itself. I have to run it one resolution higher than my desktop, which no other game has forced me too, and I have had problems installing both patches, when I have never had problems with patches before!
I am loathe to uninstall/reinstall the game, as I have a working game!
I have a retail UK version of the game, and would go to the official Witcher 2 support forums, if they had any, so once again all the technology outside of the game is giving me grief!
Lots of posts about this... Ensure you actually have 1.1 installed before doing 1.2. Many who had mods or other DLC's found they had to remove them first. I didn't.
Read through. You'll find an answer, even if it means having to re-install.