So, I just download The Witcher 2 on account of its many positive reviews on the Dope and other places.
I get it on Steam. I click “play” and then it starts installing. I then get the message " Failed to open package file ‘c:\program files (x86)\steam\steamapps\common he witcher 2\CookedPC/pack0.dzip’ " and the installing stops.
So, what do I do? Downloading it again would be a major pain; the thing is 17gigs and my monthly download limit is 60 gigs.
That file probably ended up getting corrupted during the download. I would suggest doing a file integrity check (it’s in the properties of the game in the Steam menu). It takes a while, but in theory it should identify the problem and redownload only that particular bit.
Is it installed enough where you can “verify game cache”?
That should check for then download and replace the missing/broken files so you’ll still need to use some download bandwidth.
Thanks Kobal and Trop. The game somehow started working on its own. Thread no longer useful.
Ah well, that’s good then. Happy monster slaying ! 
Play on the new “Dark” difficulty level if you’re feeling brave. I’m doing that now, and it’s really fun, so long as you remember to save often 
You also get some cool items and armor that are exclusive to that mode.