I was getting the connection error messages on the Witcher 2 launcher whenever I used it. The launcher had accepted my DLC codes as valid, but was unable to download them. I followed the instruction to delete registry keys under HKEY_CURRENT_USER\Software\CD Projekt RED\The Witcher 2\Downloads given here and as a result the launcher now connects just fine, but tells me that my codes are invalid!

Does anybody have any suggestions? I think the game itself is great, but this kind of messing about and lack of attention to detail (or actual proper game forum) just sours the whole thing for me.

Ignore the download section for now as that is broken atm
Day 1 dlc "troll trouble" is included in patch 1.1 and vendor dlc, you can get from here
http://www.gog.com/en/forum/the_witcher_2/dlc_download_from_this_topic/page1

they are also working on fixing other languages, but I dont think that works yet