TheJoe: Don't panic too much
. pack0.dzip is corrupted for some
people, why? Who the hell knows?
Anyway, I've done some digging and pack0.dzip appears to be in TW2EE_Patch-1.bin, what does that mean? You do not have to redownload the whole game!
let the installer continue after pack0.dzip, click ABORT to roll back the changes, now delete TW2EE_Patch-1.bin, run the launcher and redownload the patch. Keep doing it until dzip works. If you do not abort at the dzip stage you will have to reinstall The Witcher 2 entirely
If you're on a slow connection, you're gonna have to wait for an official solution.
thanks i'll try that.